N E B R A S K A Beef Cattle Report MP 76-A

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1 MP 76-A N E B R A S K A Tble of Contents Cow/Clf A Comprison of Beef Cttle Crossbreeding Systems Assuming Vlue-Bsed Mrketing... 3 June Versus Mrch Clving for the Nebrsk Sndhills: Production Trits... 8 June versus Mrch Clving for the Nebrsk Sndhills: Economic Comprisons June Versus Mrch Clving for the Nebrsk Sndhills: Economic Risk Anlysis Protein Supplements nd Performnce of Cows nd Clves in June-Clving Production Systems Performnce nd Economics of Winter Supplementing Pregnnt Heifers Bsed on the Metbolizble Protein System Forge Intke nd Nutrient Blnce of Heifers Grzing Sndhills Winter Rnge Summer Grzing nd Fll Grzing Pressure Effects on Protein Content nd Digestibility of Fll Rnge Diets Annul Forge Production nd Qulity Trils Growing Compenstory Growth nd Slughter Brekevens of Yerling Cttle Undegrdble Intke Protein Supplementtion of Compensting, Grzing Steers Undegrdble Intke Protein Content of Corn Steep Compred to Soyben Mel Utiliztion of Bt Corn Hybrids in Growing Beef Steers Wet Corn Gluten Feed Supplementtion of Clves Grzing Corn Residue.. 41 Impct of Grzing Corn Stlks in the Spring on Crop Yields Finishing Economic Returns of Wet Byproducts s Cttle Feed Urinry Allntoin Excretion of Finishing Steers: Effects of Grin Adpttion nd Wet Milling Byproduct Feeding Progrmmed Gin Finishing Systems In Yerling Steers Fed Dry-rolled Corn Or Wet Corn Gluten Feed Finishing Diets Economic Evlution of Corn Processing for Finishing Cttle Effect of Corn Processing on Degrdble Intke Protein Requirement of Finishing Cttle High Moisture nd Dry-Rolled High-Oil Corn for Finishing Feedlot Steers Beef Cttle Report Agriculturl Reserch Division University of Nebrsk Coopertive Extension Institute of Agriculture nd Nturl Resources University of Nebrsk-Lincoln Corn Processing Method in Finishing Diets Contining Wet Corn Gluten Feed Implnt Progrms for Feedlot Heifers Using Synovex PlusTM The Effect of Feeding Pressed Sugr Beet Pulp in Beef Cttle Feedlot Finishing Diets Effects of Feeding Regimen on Performnce, Behvior nd Body Temperture of Feedlot Steers Restricted Feeding Strtegies for Reducing Het Lod of Yerling Steers Mnging Het Stress in Feedlot Cttle Using Sprinklers The Reltionship of the Chrcteristics of Feedlot Pens to the Percentge of Cttle Shedding Escherichi coli O157:H7 Within the Pen A Dignostic Strtegy to Clssify Pens of Feedlot Cttle by the Prevlence of Escherichi coli O157:H7 Fecl Shedding Influence of Restricted Intke nd Reduced Dietry Strch on Colonic ph nd E. coli Prevlence Phosphorus nd Nitrogen-Bsed Beef Cttle Mnure or Compost Appliction to Corn Composting of Feedlot nd Diry Mnure: Compost Chrcteristics nd Impct on Crop Yields Beef Products Consumer Acceptnce nd Vlue of Strip Steks Differing in Mrbling nd Country-of-Origin Physicl nd Chemicl Properties of 39 Muscles from the Beef Chuck nd Round Fiber Type Composition of the Beef Chuck nd Round The Effects of Post-Hrvest Time nd Temperture on Glycolytic Potentil of Beef Muscle The Role of Muscle Glycogen in Drk Cutting Beef New Technology Dietry Conjugted Linoleic Acids (CLA) nd Body Ft Chnges Chnges to the Purine Assy Improve Purine Recovery nd Assy Precision Urinry Allntoin Excretion s Mrker of Microbil Crude Protein Supply for Cttle Evlution of 1996 Beef Cttle NRC Model nd Development of Net Energy Modifiers

2 ACKNOWLEDGMENTS Apprecition is expressed to the following firms, ssocitions, or gencies who provided grnt support for reserch in the beef cttle progrm. Americn Proteins, Atlnt, GA Novrtis Seeds, Golden Vlley, MN Biotol Inc., Eden Pririe, MN Nebrsk Beef Council, Kerney, NE Crgill Corn Milling, Blir, NE Nebrsk Technology Development Corp., Lincoln, NE Elnco Animl Helth, Indinpolis, IN Optimum Qulity Grins, Urbndle, IA Frmlnd Industries, Knss City, MO Roche Vitmins Inc., Prker, CO Fts nd Proteins Reserch Foundtion, Chicgo, IL Soypss Roylty Funds, University of Nebrsk, Lincoln, NE Intervet, Millsboro, DE UNL Reserch Council, Lincoln, NE Lignotech, Rothschild, WI U.S. Poultry nd Egg Assoc., Atlnt, GA LB1206, Prehrvest E. coli 0157:H7 Reserch, Lincoln, NE Apprecition is lso expressed for the following firms who provided products or services. Crgill Corn Milling, Blir, NE Iow Limestone Co., Des Moines, IA Elnco Animl Helth, Indinpolis, IN Lignotech, Rothschild, WI Excel Corp., Schuyler, NE Liquid Feed Commodities, Fremont, NE Fort Dodge Animl Helth, Overlnd Prk, KS SEM Minerls, Quincy, IL IBP Inc., Dkot Dunes, SD Stock Food Corportion, Mriett, GA Intervet, Millsboro, DE Western Sugr, Scottsbluff, NE Apprecition is lso expressed to the following reserch technicins, unit mngers, nd crew involved in the reserch progrms t our vrious loctions. Agriculturl Reserch nd Development Center, Ithc Animl Science Deprtment, Lincoln Jeff Bergmn Don McClure Glen Erickson Rosemrie Rosrio Mrk Blckford Allison Miller Jeryl Huptmn Clvin Schrock Bob Broweleit Krl Moline Jnet Hyde Cndice Toombs Rob Cooper Ken Rezc D.J. Jordon Csey Wilson Logn Dn Jon Simon Clyde Nber Terry Kmphus Doug Wtson Gudmundsen Sndhills Lbortory, Whitmn Pnhndle Reserch nd Extension Center, Scottsbluff Andy Applegrth John Nollette Nbor Guzmn Pul McMillen Jckie Musgrve Troy Smith West Centrl Reserch nd Extension Center, North Pltte Dlbey-Hlleck Frm Tom Arensdorf Russell Sndberg Mrk Drgstin Rex Dvis Northest Reserch nd Extension Center, Norfolk Wnd Cerkoney Kevin Heithold Bob Frerichs Lee Johnson It is the policy of the University of Nebrsk-Lincoln not to discriminte on the bsis of gender, ge, disbility, rce, color, religion, mritl sttus, vetern s sttus, ntionl or ethnic origin or sexul orienttion Nebrsk Beef Report Pge 2

3 A Comprison of Beef Cttle Crossbreeding Systems Assuming Vlue-Bsed Mrketing U. Jon Tomsen D. Kirk Drnell Merlyn Nielsen 1 Optiml use of beef breeds nd crossing systems depends on totl-industry net returns, not just vlue of crcsses. Level of feed requirements, milk production nd other performnce chrcteristics re importnt in determining industry vlue. Summry This study simulted totl life-cycle expenses nd income under vlue-bsed mrketing to rrive t predicted net returns for crossbreeding systems. The simultion used deterministic model of totlly contined beef breeding systems nd evluted 14 breeds nd their crosses from biologicl dt collected t the U.S. Met Animl Reserch Center in Nebrsk. Compring beef cttle crossbreeding systems under vluebsed mrketing will id us in understnding the interctions of the totl system. Besides vlue of crcsses, feed requirements, level of milk production nd other chrcteristics re importnt in determining net returns. Introduction For the evlution of breeds nd crosses, the beef cttle industry should not simply bse decisions on crcss vlue. Rther, considertion needs to be given to totl life-cycle expenses nd income. For exmple, breeds or crosses tht hve the highest crcss vlue might lso hve the highest production costs due to poorer reproduction nd/or higher mintennce feed costs. The system lso should evlute full, totlly contined, sustinble, crossing system (i.e., one tht contins ll necessry purebred nd crossbred groups). The purpose of this study ws to simulte biologicl nd then economic outcomes under vluebsed mrketing for severl breeding systems. All systems were simulted for two mrketing scenrios for fed clves: equl ge t slughter nd equl bckft t slughter. Procedure Fourteen breeds nd their crosses were simulted using biologicl performnce derived from severl dt reports from the Germ Plsm Utiliztion nd the Germ Plsm Evlution projects, conducted t the U.S. Met Animl Reserch Center ner Cly Center, Neb. The 14 breeds were: Hereford, Angus, Simmentl, Limousin, Chrolis, Brhmn, Red Poll, Gelbvieh, Mine Anjou, Brunvieh, Chinin, Brngus, Pinzguer nd Trentise. In ddition, reports from other literture lso were incorported to set levels of individul nd mternl heterosis for the simultion nd to predict heifer performnce from steers. Simultions were done using deterministic model (i.e., ll performnce ws bsed on verges within breed or cross with no vrition between nimls) encompssing conception through slughter. All systems were simulted using n equl resource bse. The stndrd resource bse ws n equl use of summer psture. For the 14 pure breeds, the number of AUM s per 1,000-cow herd ws simulted. The verge of these 14 purebred systems with 1000 breeding femles becme the stndrd bse of AUM usge. After estblishing the stndrd bse, the totl number of cows in ech totl system, including ll purebred systems, ws vried to equlize use of the stndrd psture resource. This work simulted purebred, twobreed rottion, three-breed rottion, rotterminl, nd four-breed composite systems, using the 14 breeds. The rottionl nd rot-terminl systems were totlly contined beef breeding systems. Seprte breeding groups were prt of the totl rottionl systems nd were ssumed to produce purebred breeding nimls (bulls) needed for the rest of the system. The rot-terminl system ssumed two-breed rottion to generte replcement femles plus terminl crossing to third breed of sire to produce only slughter nimls. Thus for rotterminl system, there would be three purebred groups (two to produce bulls for the two-breed rottion plus one to produce bulls for the terminl cross) in ddition to the crossbred groups tht mde up the totl system. The four-breed composite ws ssumed to be lredy creted, thus only one breeding group ws simulted. The system simulted conception through slughter. Clving ws in the spring, wening ws t 205 dys, nd clves immeditely entered the feedlot for feeding until slughter. The verge dys fed for the biologicl dt from the U.S. Met Animl Reserch Center ws 235 dys with slughter t 440 dys. Output ws initilly generted for n equl number of dys fed (235) nd equl ge t slughter (440 dys). These outcomes re clled Equl Age. Purebred groups vried widely in bckft nd yield grde when slughtered t n equl ge. Thus, nother mngement scenrio ws simulted where genetic groups of nimls were fed different numbers of dys nd then slughtered t the sme bckft. Outcomes under this mngement re clled Equl Ft. Becuse this required further extrpoltion from the biologicl dt bse nd minimizing (Continued on next pge) Pge Nebrsk Beef Report

4 the mount of extrpoltion is desired, the verge bckft of purebred groups in the Equl Age scenrio ws used s the slughter endpoint in the Equl Ft scenrio. For steers, this ws.24 in, nd for heifers, the endpoint ws.28 in. Numbers of steers nd heifers fed directly for slughter vried for ech system nd were function of the totl size of the system s determined by the constnt psture resource bse, the reproductive rte nd the number of breeding bulls (purebred nd composite systems nd segments of rottionl systems) nd replcement heifers needed (purebred nd composite systems plus rottionl segments of rottionl nd rotterminl systems). Feedlot income, cowherd income, feedlot costs nd cowherd costs were totled nd totl income minus totl costs yielded predicted net returns of ech system. Vrious input costs nd output vlues were derived from 10- yer verges for Nebrsk. Fifteen trits were used in the simultions. Mny of these 15 trits incorported differences in 2-yer-old, 3-yer-old, nd mture dms to help evlute the cow herd. For the crossbreeding systems to be evluted, individul nd mternl heterosis estimtes were determined for ech of the 15 trits. An ge distribution for the cow herd ws simulted, bsed on reproductive rte nd culling of ll non-pregnnt femles t wening time to produce income. All cows were ssumed culled for slvge t 8.5 yers of ge. Clf losses were simulted t vrious times of the production yer, nd cows not nursing clf were culled to generte income. Trits simulted cn be subdivided into growth nd body weights, energy requirements, milk production, reproduction nd crcss chrcteristics. Tbles 1 (clf nd cow weights, milk production, reproduction nd clving difficulty), 2 (feed energy requirements), 3 (crcss chrcteristics nd vlue under Equl Age slughter), nd 4 (crcss chrcteristics nd vlue under Equl Ft slughter) contin purebred vlues for smples of the trits. Vlue per pound of crcss for slughter steers nd heifers ws bsed on yield grde, mrbling nd breed type using regression equ- Tble 1. Purebred niml weights (1b), milk production (lb/205 dys), reproductive performnce nd clving difficulty used in simultions. Breed Birth weight 200-dy Breeding Milk % wened % clving weight weigiht femle production of exposed difficulty mture mture mture mture mture 2-yer-old dm,b dm,b weight dm dm dm c Hereford Angus Simmentl Limousin Chrolis Brhmn Red Poll Gelbvieh Mine Anjou Brunvieh Chinin Brngus Pinzguer Trentise Dt simulted for 2-yer-old, 3-yer-old, nd mture dms; dt from only mture dms shown here. b Averge for steers nd heifers. c Dt simulted for 2-yer-old, 3-yer-old, nd mture dms; dt from only 2-yer-old dms shown here. Tble 2. Purebred energy requirements nd milk production used in the simultions. Breed Mintennce Prewening Feedlot Feedlot energy gin energy gin energy b gin energy c Kcl/kg.75 /dy Mcl/lb Mcl/lb Mcl/lb Hereford Angus Simmentl Limousin Chrolis Brhmn Red Poll Gelbvieh Mine Anjou Brunvieh Chinin Brngus Pinzguer Trentise Non-lctting, gestting cow; ll other cow nd clf simulted mintennce costs derived from this bse vlue. b Dt simulted for steers nd heifers; steer dt shown here for Equl Age slughter scenrio. c Dt simulted for steers nd heifers; steer dt shown here for Equl Ft slughter scenrio. Tble 3. Purebred steer crcss chrcteristics used in Equl Age (440 dys) t slughter simultions. Breed Yield grde Mrbling score Crcss weight, lb Vlue, $/lb Hereford Angus Simmentl Limousin Chrolis Brhmn Red Poll Gelbvieh Mine Anjou Brunvieh Chinin Brngus Pinzguer Trentise Heifer dt were simulted from steer dt Nebrsk Beef Report Pge 4

5 Tble 4. Purebred steer crcss chrcteristics used in Equl Ft (.24 in) t slughter simultions. Breed Dys fed Yield grde Mrbling score Crcss weight,lb Vlue, $/lb Hereford Angus Simmentl Limousin Chrolis Brhmn Red Poll Gelbvieh Mine Anjou Brunvieh Chinin Brngus Pinzguer Trentise Heifer dt were simulted from steer dt. Tble 5. Averge net returns ($) under Equl Age t slughter scenrio for ll crosses in system nd for selected crosses in ech system. System Averge of ll Averge of top 10 b Averge of bottom 10 c Purebred 32,246 42,787 17,134 Two-breed rottion 41,450 51,175 28,975 Three-breed rottion 43,647 54,117 31,587 Rot-terminl 42,700 54,829 26,407 Composite 41,998 52,076 30,985 All crossing systems re totlly sustining, thus including ll necessry purebred groups. Rot-terminl hs two-breed rottion plus terminl cross. Composite hs equl prts of four breeds. All systems hve equl use of psture resource derived from the verge resource required for the fourteen 1000-cow purebred systems. b Top 3 for purebreed. c Bottom 3 for purebred. tions developed in reserch work t Texs A&M (Griffin et l., 1989). Results Equl Age t Slughter Tble 5 contins verge net returns of the 14 purebreds, 91 possible (14!/[2! 12!]) two-breed rottions, 364 possible (14!/[3! 11!]) three-breed rottions, 1092 possible (14!/[2! 1! 11!]) rot-terminls, nd 1001 possible (14!/[4! 10!]) composites under the Equl Age slughter scenrio. Becuse the systems were defined to hve n rbitrry but equl psture resource usge, net returns s presented re comprble on reltive bsis. Overll, the three-breed rottion nd rot-terminl were the most profitble systems under this scenrio. These systems cpitlize on pprecible mounts of heterosis. The four-breed composite lso would hve high mount of heterosis, but it ws constrined to hve four breeds compred to the threebreed rottion nd rot-terminl tht contined three. Purebreeding ws the lest profitble system, losing out on the desirble benefits from heterosis. Tble 5 lso contins verges for net returns of the top 10 nd bottom 10 in ech of the crossing systems plus verges for the top nd bottom three purebreds for the Equl Age slughter scenrio. The verge of ll three-breed rottions ws slightly higher thn for ll rot-terminls. But for the top 10 verges, the rot-terminl systems fred better thn the three-breed rottions. Cpitlizing on terminl crossing, especilly with differentil vlues of crcsses, ws beneficil. Four-breed composite nd three-breed rottion were the lest risky systems becuse these were more profitble mong the lest profitble. Tble 6 contins the top 10 crosses for ech crossbreeding system under the Equl Age slughter scenrio. Differences in net returns mong the top 10 crosses within system were not lrge, especilly for those in the rot-terminl system. The top ten rot-terminls hd five different breeds of terminl sire represented. Breeds tht were included in mny of the top crossing systems were: Chrolis, Gelbvieh, Limousin, (Continued on next pge) Tble 6. Top ten crosses in ech system b on the bsis of their net returns c ($) for Equl Age (440 dys) t slughter scenrio. Two-breed rottion Three-breed rottion Rot-terminl Composite Cross Net Cross Net Cross d Net Cross Net CA*MA 52,876 LM*CA*MA 55,618 CA MA*TA 55,746 LM*CA*MA*TA 54,207 LM*MA 52,675 LM*MA*TA 55,330 LM MA*TA 55,580 LM*CA*GV*MA 52,959 MA*TA 52,406 CA*MA*TA 55,209 LM CA*MA 55,185 LM*GV*MA*TA 52,709 LM*CA 52,254 LM*CA*TA 55,087 GV MA*TA 55,107 CA*GV*MA*TA 52,637 CA*TA 52,063 LM*GV*MA 53,715 SM MA*TA 54,831 LM*CA*GV*TA 52,550 LM*TA 51,829 CA*GV*MA 53,515 GV CA*MA 54,701 SM*LM*CA*MA 51,274 GV*MA 49,821 LM*CA*GV 53,482 SM CA*MA 54,421 LM*CA*MA*PG 51,211 CA*GV 49,486 GV*MA*TA 53,141 BV MA*TA 54,315 LM*CA*MA*BV 51,206 LM*GV 49,468 LM*GV*TA 53,134 CA AN*MA 54,266 AN*LM*CA*MA 51,015 GV*TA 48,876 CA*GV*TA 52,938 CA GV*MA 54,135 SM*LM*MA*TA 50,989 Breed codes: AN = Angus, BV = Brunvieh, CA = Chrolis, GV = Gelbvieh, LM = Limousin, MA = Mine Anjou, PG = Pinzguer, SM = Simmentl, nd TA = Trentise. b All systems re totlly sustining, including necessry purebred groups. c Net returns bsed on n equl use of psture resources (verge of 1000-cow purebred systems) nd cn be compred on reltive bsis. d Terminl sire breed nd two-breed rottion dm breeds. Pge Nebrsk Beef Report

6 Mine Anjou nd Trentise. On purebred crcss vlue, these five breeds verged 1.6% higher vlue per pound thn the other nine breeds. Equl Ft t Slughter Tble 7 contins the verge net returns of the 14 purebreds, 91 twobreed rottions, 364 three-breed rottions, 1,092 rot-terminls, nd 1,001 composites under the Equl Ft slughter scenrio. Overll, the three-breed rottion nd composite were the most profitble systems under this scenrio. These systems cpitlize on pprecible mounts of heterosis, with substntil benefits coming through incresed reproductive performnce nd incresed rte of growth. Consistent with the Equl Age slughter scenrio, purebreeding ws the lest profitble system, losing out on the desirble benefits from heterosis. Tble 7 lso contins the verges for net returns of the top 10 nd bottom 10 in ech of the crossing systems plus the verges for the top nd bottom three purebreds for the Equl Ft slughter scenrio. The verges of ll three-breed rottions nd of ll composites were slightly higher thn for ll rot-terminls. But for the top 10 verges, the rot-terminl systems fred better thn the three-breed rottions nd the composites. Being ble to cpitlize on terminl crossing, gining the benefit of lrger clf size reltive to cow size in some systems, ws beneficil. Four-breed Tble 7. Averge net returns ($) under Equl Ft t slughter scenrio for ll crosses in system nd for selected crosses in ech system. System Averge of ll Averge of top 10 b Averge of bottom 10 c Purebred 36,077 45,662 20,703 Two-breed rottion 49,121 60,459 36,411 Three-breed rottion 55,404 69,711 38,622 Rot-terminl 51,771 70,757 32,992 Composite 53,971 68,757 38,783 All crossing systems re totlly sustining, thus including ll necessry purebred groups. Rot-terminl hs two-breed rottion plus terminl cross. Composite hs equl prts of four breeds. All systems hve equl use of psture resource derived from the verge resource required for the fourteen 1000-cow purebred systems. b Top 3 for purebreed. c Bottom 3 for purebred. composite nd three-breed rottion were the lest risky systems becuse these were more profitble mong the lest profitble. Tble 8 contins the top 10 crosses for ech of the crossbreeding systems under the Equl Ft slughter scenrio. Differences in net returns mong the top 10 crosses within system were not s lrge in the composites s in the systems tht used rottionl crossing. The top 10 rot-terminls hd six different breeds of terminl sire represented. Breeds tht were included in mny of the top crossing systems were: Angus, Chrolis nd Gelbvieh. On purebred crcss vlue, these three breeds verged slightly less vlue per pound thn the other 11 breeds. Thus vlue per pound of crcss hd little or no influence on the vlue of breeds in crossing systems in the Equl Ft slughter scenrio. Choices mong breeds to use in crossing systems should be bsed on their overll contribution to totl system net returns. There were 78 different combintions of crossbred dms for ech terminl sire in the rot-terminl systems. Tble 9 lists verge net returns for the top 10 breeds when used s terminl sires in the rot-terminl systems nd the top 10 two-breed rottions used for dms in the rot-terminl systems under the Equl Ft slughter scenrio. As terminl sires, Simmentl, Gelbvieh nd Chrolis rnked s the top breeds. Angus ws included s prt of the dmbreed rottion in ll of the top 10 rot-terminl systems. Discussion As with ny simultion, results depend on the ssumed models nd dt s well s the mrketing system. All systems tht were simulted hd constnt mount of summer psture usge for the cow-clf herd. This resulted in vrying numbers of cows for the different crossbred nd purebred groups. For Tble 8. Top ten crosses in ech system b on the bsis of their net returns c ($) for Equl Ft t slughter scenrio. Two-breed rottion Three-breed rottion Rot-terminl Composite Cross Net Cross Net Cross d Net Cross Net AN*CA 64,906 AN*CA*GV 74,250 SM AN*GV 73,559 AN*LM*CA*GV 70,671 AN*GV 63,872 HE*CA*GV 72,366 GV AN*CA 73,335 AN*SM*CA*GV 69,586 HE*CA 62,598 AN*LM*CA 70,352 CA AN*GV 73,236 AN*CA*GV*MA 69,540 HE*GV 61,613 AN*LM*GV 69,961 SM AN*CA 72,577 HE*LM*CA*GV 69,194 CA*MA 60,345 AN*SM*CA 69,291 BV AN*GV 69,891 AN*CA*GV*PG 68,747 CA*TA 59,589 AN*SM*GV 68,759 LM AN*GV 69,649 HE*CA*GV*MA 68,544 GV*MA 58,784 CA*GV*MA 68,596 BV AN*CA 69,354 AN*CA*GV*TA 68,526 GV*TA 57,897 HE*LM*CA 67,956 LM AN*CA 69,129 HE*SM*CA*GV 68,479 AN*LM 57,729 CA*GV*TA 67,855 PG AN*GV 68,446 AN*CA*GV*BV 68,144 AN*SM 57,261 AN*CA*PG 67,724 GV AN*MA 68,390 HE*AN*CA*GV 67,929 Breed codes: AN = Angus, BV = Brunvieh, CA = Chrolis, HE=Hereford, GV=Gelbvieh, LM = Limousin, MA = Mine Anjou, PG = Pinzguer, SM = Simmentl, nd TA = Trentise. b All systems re totlly sustining, including necessry purebred groups. c Net returns bsed on n equl use of psture resources (verge of 1000-cow purebred systems) nd cn be compred on reltive bsis. d Terminl sire breed nd two-breed rottion dm breeds Nebrsk Beef Report Pge 6

7 Tble 9. Top ten terminl-sire breeds nd top ten dm-breed rottions for net returns ($) verged cross rot-terminl systems for Equl Ft t slughter scenrio. Terminl Sire Net Returns Dm Rottion Net Returns Simmentl 57,085 Angus*Gelbvieh 66,052 Gelbvieh 56,429 Angus*Chrolis 66,041 Chrolis 55,364 Hereford*Gelbvieh 61,917 Brunvieh 54,270 Hereford*Chrolis 61,141 Limousin 53,673 Chrolis*Mine Anjou 60,707 Pinzguer 53,064 Angus*Mine Anjou 60,474 Chinin 51,613 Gelbvieh*Mine Anjou 60,353 Mine Anjou 51,362 Angus*Pinzguer 59,664 Trentise 51,352 Angus*Simmentl 59,587 Brngus 49,985 Angus*Limousin 59,571 All systems re totlly self sustining, including necessry purebred groups. exmple, the number of breeding femles including replcement heifers, set to verge 1,000 totl breeding femles, rnged in the purebreeding systems from 915 for Chinin to 1,216 for Hereford. Likewise, numbers of nimls sold for income (cull femles from the reproducing herd nd fed steers nd heifers) rnged widely too. Severl slughter/mrketing endpoints re possible. The esiest endpoint to simulte ws the Equl Age t slughter (440 dys). Becuse the biologicl dt on feedlot performnce nd crcss chrcteristics were vilble on constnt-time bsis, simultion ws reltively strightforwrd. The Equl Age scenrio lso is the esiest to follow for producer trying to mke comprisons using rel, not simulted, cttle: It is very esy to designte fixed number of dys on feed nd ge t slughter nd then follow tht. But, the rnge in crcss ftness t the Equl Age endpoint ws lrge in the systems simulted under tht scenrio (e.g., purebred steers rnged in yield grde from 1.89 to 3.46, Tble 3). Thus, the Equl Age scenrio is probbly not relistic scenrio for compring possible performnce of different systems. The Equl Ft (.24 in for steers nd.28 in for heifers) is more relistic nd provides much better bsis for comprison. Producers cn, through use of ultrsound or visul pprisl nd experience, identify nimls tht re t the desired endpoint with resonble ccurcy. The differences between breeds nd crossing systems in crcss vlue per pound re diminished when crcsses hve the sme outside ft. A possible wekness of the simultions under this Equl Ft scenrio is liner djustments, unique for ech breed, were used to derive the crcss chrcteristics in Tble 4 from those in Tble 3. Becuse there were wide differences in bckft when slughtered t 440 dys of ge, lrge differences then hd to be simulted in dys on feed to ttin the trget Equl Ft endpoints. Note in Tble 4, tht the different breeds of steers vried from 178 dys on feed (slughter t 383 dys old) to 319 dys of feed (slughter t 524 dys old). Vrition in vlue of slughter nimls from the feedlot ws importnt in both scenrios but in different wys. The correltion between the verge net returns for terminl sire breeds in rotterminl systems nd the vlue per steer ws.94 in the Equl Age scenrio nd.96 in the Equl Ft scenrio. But the correltion between the verge net returns of terminl sire breeds in rot-terminl systems nd the price per pound of crcss ws.85 in the Equl Age scenrio nd only.31 in the Equl Ft scenrio. Thus under n Equl Ft scenrio, price per pound of crcss hd very limited influence on net returns for the system. Yet nother mrketing scenrio could be exmined, but it would require even further extrpoltion nd ssumption. Assigning slughter endpoints for breeds nd crosses bsed on mximizing net returns would pper to be the most useful for ultimte decision-mking in our industry. This would require ssessing net returns for ech cross in ech system for vrible dys on feed, nd then mximizing to set the endpoint. In the bsence of this other scenrio, net returns under the Equl Ft endpoint is our most useful scenrio for mking industry breeding decisions. Breeds with high mintennce energy requirements generlly did not surfce s top mternl-use breeds. Cow size ws not n importnt determiner of net returns for mternl use. Likewise, breeds with higher milk production levels did not rnk well for mternl use. Breeds with the hevier slughter weights t the trget bckft rnked s the top terminl-sire breeds. A mrketing system tht ssigns vlue to individul crcsses nd relys this informtion bck to producers will ffect choices of crossing systems plus influence selection nd mngement decisions. By compring beef cttle crossbreeding systems ssuming vlue-bsed mrketing we cn better understnd the interctions of the totl system. 1 U. Jon Tomsen, former grdute student; D. Kirk Drnell, former grdute student; Merlyn Nielsen, professor, Animl Science, Lincoln. Pge Nebrsk Beef Report

8 June Versus Mrch Clving for the Nebrsk Sndhills: Production Trits Don Adms Dick Clrk Russ Sndberg Gordon Crriker Terry Klopfenstein Todd Milton 1 Mtching clving with growth of nturl forges by moving trditionl Mrch clving to June resulted in substntilly lower mount of hy fed nd less lbor to produce clf. Summry Our objective ws to determine if lbor nd purchsed inputs could be reduced nd profitbility improved by mtching lcttion (i.e., clving dte) with nutrient content of grzed forges to extend the grzing seson in beef cow/clf systems. By djusting trditionl Mrch clving dte to nontrditionl June clving dte, nerly 2 tons of hrvested feed/cow ws replced by grzing. Feeding nd clving lbor inputs of mture cows were 61% lower for the June clving compred to the Mrch clving system. Wening rtes were comprble between Mrch nd June clving systems. Wening weights for June-born clves were 70 lbs lighter thn Mrch-born clves. Introduction The mount of hrvested nd purchsed feeds required to sustin cow herd is highly correlted with clving dte. Clving in Februry nd/or Mrch in the Nebrsk Sndhills results in the high nutrient requirements for lcttion occurring when nutrient content of rnge forges re low. Thus, significnt inputs of hrvested nd processed feeds re required to ensure tht high percentge of cows rebreed nd produce clf the following yer. We hypothesized tht June clving dte would mtch the high nutrient lcttion requirements of the cow with high nutrient content of immture growing plnts nd extend grzing compred to trditionl Mrch clving dte. Our primry objective ws to determine if hrvested nd/or purchsed feeds nd lbor could be reduced nd sustinbility nd profitbility improved by mtching lcttion (i.e. clving dte) with nutrient content of grzed forges in beef cow/clf systems. Procedure In 1993, cows from Mrch clving cow herd were bred to clve beginning either Mrch 15 (75 cows) or June 15 (120 cows). Steer clves from Mrch clving were finished s clf-feds. Onehlf of the steer clves from June clving were finished s clf-feds nd one-hlf grzed summer Sndhills rnge s yerlings before being finished. Clving dtes, wening dtes, nd feeding periods re given in Tble 1. Only mture cows were used in this study. Heifer clves re being developed for replcements nd reserch is ongoing. June clving cows were split into two groups for the breeding seson. One group ws bred on subirrigted medow regrowth (60 cows) nd the other on uplnd rnge (60 cows). Breeding seson ws 60 dys for Mrch clving cows nd 45 dys for June clving cows. Wening rtes were clculted ccording to Stndrdized Performnce Anlysis (SPA) guidelines nd were the sme for the Mrch nd June systems. Becuse of potentil bis from conversion of cows from Mrch to June clving cycle, pregnncy rtes during yers 1993 nd 1994 were not included in dt nlysis. Animl production nd resource use (grzing, feed, nd lbor) records were mintined on ech cow-clf herd from breeding through to slughter through 1999 (4 production cycles). Mrch clving cows were fed hy from subirrigted medows bout mid-jnury through April. June clving cows were fed medow hy for three dys fter wening nd during winter storm. Results Mtching clving with growth of nturl forges substntilly reduced the mount of hy fed (Tble 2). Over four yers bout 2 tons of hy were fed to Mrch clving cows nnully compred to bout.1 ton of hy for June clving cows. However, bout 60 lb/cow more protein supplement ws fed to June clving cows nnully thn Mrch clving cows. Lbor for feeding nd clving to produce wened clf in the June system ws 61% lower thn the Mrch system (Tble 2). In ddition to differences in resource use shown in Tble 3, clving building commonly used in the trditionl Mrch system is not needed in the June system. Post-wening resource requirements for clf feds (hy nd supplement to prepre wened clf for shipment to the feedlot) were higher in Tble 1. Approximte dtes for Mrch nd June clving systems. Mrch June Item Clf feds Clf feds Yerlings Breed cows June-August September-October September-October Clving Mrch-April June-July June-July Wen September 26 Jnury 9 Jnury 9 Steers Onto Grss June 3 Steers Into Feedlot November 13 Februry 13 September 12 Slughter My 22 August 19 Jnury Nebrsk Beef Report Pge 8

9 Tble 2. Averge resource use per hed for Mrch nd June clving systems 1995 to Mrch June Clf feds Yerlings Resource use Clf feds Rnge Medow Rnge Medow Cows Hy (tons) Purchsed feed (lb) Grzing dys (rnge) Grzing dys (medow) Feeding lbor (hr) Clving lbor (hr) Clves (wen to on grss/feedlot) Hy (tons) Purchsed feed (lb) Grzing dys (rnge) Feeding lbor (hr) Yerlings (on grss to feedlot) Grzing dys (rnge) Clves/Yerlings (in feedlot) Feedlot dys Tble 3. Pregnncy rte nd wening rte (percentge of cows exposed to the bull) of cows in Mrch nd June clving systems. Mrch clving June Clving Item Rnge Medow Pregnncy rte, % Wening Rte, % Mens were similr (P>.10) for Mrch vs. June systems nd for medow vs rnge during the breeding seson within the June clving system. Tble 4. Averge weights nd ADGs for Mrch nd June clving systems Mrch June Clf feds Clf feds Yerlings Weights t: Rnge Medow Rnge Medow Wen, lb ADG wen to grss/feedlot, lb On to Grss ADG on grss to feedlot, lb Into Feedlot, lb ADG in feedlot, lb Slughter (live wt.), lb Slughter (live wt.) = hot crcss weight.62. the June system. Mrch-born clves grzed subirrigted medow between wening nd the feedlot while June-born clves were fed hy nd protein supplement. Clves grown s yerlings in the June clving system required more supplement, hrvested forge, nd grzing thn June- or Mrch-born clf-feds but were finished in the feedlot bout eight weeks fster. Pregnncy rte nd wening rte re reported in Tble 3. Pregnncy rte nd wening rte were similr (P>.10) for Mrch vs. June clving nd for June clving cows bred on subirrigted regrowth nd uplnd rnge. Clf wening weights nd verge dily gin (ADG) were different between Mrch nd June clving nd between clves June clving tht grzed subirrigted medow nd rnge during the breeding seson (Tble 4). Juneborn steer clves were bout 50 to 70 lb lighter (medow- nd rnge-bred tretments, respectively) t wening thn Mrch-born steer clves. The lower wening weight of June-born clves compred to Mrch-born clves is best explined by low clf gins produced on the low qulity forges typicl of Sndhills rnge during November through Jnury. The ADG ws greter for the Mrch-born clves thn Juneborn clves during bckgrounding between wening nd shipment to the feedlot. However, ADG in the feedlot ws higher for the June-born clf feds. Live weights t slughter were higher for the Mrch-born clf feds. A greter percentge of the crcsses from the Mrch system grded Choice (53%) thn the June system (33%). Sixty-six percent of the June system yerling crcsses grded Choice or upper 2/3 Choice. Crcss yield grdes were 3 or less in ll systems. Mtching clving dte to immture, nutrient dense forges reduced the mount of hy fed nd clving nd feeding lbor compred to Mrch clving without reducing wening rte. Although wening weight ws lower for June-born thn Mrch-born clves, the lbor nd feed svings ppered to offset the lower wening weight. We emphsize tht the June clving dte ws selected s mens to mtch nutrient requirements of the cow with nutrients in grzed forges. Other clving dtes re likely to be selected to mtch nutrient requirements of the cow with forge nutrients in other geogrphicl res. Adption of n lternte clving seson should be bsed on expected returns nd rnch resources. 1 Don Adms, professor Animl Science; Dick Clrk, professor Agriculturl Economics; Russ Sndberg, reserch technicin Animl Science; Gordon Crriker, former reserch ssocite, Agriculturl Economics, West Centrl Reserch nd Extension Center, North Pltte; Terry Klopfenstein, professor Animl Science, nd Todd Milton, ssistnt professor, Lincoln. Pge Nebrsk Beef Report

10 June versus Mrch Clving for the Nebrsk Sndhills: Economic Comprisons Gordon Crriker Dick Clrk Don Adms Russ Sndberg 1 A June clving system extended grzing, reduced feed costs, reduced lbor inputs nd hd higher net returns thn Mrch clving system. Summry Costs nd returns of June nd Mrch clving systems were compred t four production phses. Finncil costs of the June system were lowest, due primrily to lower costs of producing wened clf. Post-wening finncil nd economic costs t ech phse were nerly identicl. Selling June-born steer clves t Jnury wening would double net returns compred to selling Mrch-born steer clves t October wening due to lower costs nd higher mrket prices. Net returns for Juneborn steer clves retined beyond wening re highest if clves re retined s yerlings nd finished. Clves finished s clf-feds provided the highest net returns for the Mrch clving system. Introduction Input requirements for the June system re lower t some phses thn those for the Mrch system s described in the previous rticle, June versus Mrch Clving for the Nebrsk Sndhills: Production Trits. The objectives of this reserch were to: 1) develop cost budgets for ech system nd compre the costs t severl production phses in the two systems; nd 2) develop net returns budgets for ech system nd compre the net returns t severl production phses in the two systems. We hypothesized tht the June system costs would be lower nd net returns higher thn those for the Mrch system. Procedure Finncil cost budgets were developed for ech system through wening. Economic nd finncil cost budgets were then developed for ech production phse fter wening. Budgets were bsed on the 4-yer ( ) verge resource use during ech phse nd 1998 input prices. All budgets include costs for hrvesting hy nd purchsed feed, grzing (fence nd wter mintennce, livestock checking, etc.), lbor, operting interest, mngement, overhed nd heifer replcement. The budgets do not include chrges for lnd, property txes, insurnce, or buildings. Ownership costs for hy hrvesting nd feeding equipment, but not other equipment, re included. Bsed on other reserch t GSL it ws determined tht the sme lnd bse (bout 90% uplnd nd 10% subirrigted medows) could support equivlent numbers of cows yer round for either system. Therefore, lnd chrges nd txes would be the sme. The Mrch clving system would use the medows for hy production while the June clving system would use them for summer nd some spring nd fll grzing. The economic costs for ll phses beyond wening reflect the opportunity costs of growing the steer clf during production phse by lso including the vlue of the incoming niml s if it ws purchsed t mrket. Vluing the steer clf t the beginning of ech phse of production permits ech phse to be evluted independently, s if ech phse ws n independent enterprise. The finncil costs reflect the ccumulted csh costs of growing the steer clf through prticulr production phse. Annul net returns budgets were developed using the cost budgets, verge nnul steer weights t the end of ech production phse, nd 1992 through 1998 rel (deflted mrket prices) prices received t western- Nebrsk nd estern-wyoming uctions. Potentil selling strtegies for the clf crops were determined bsed on the vrious production phses. The economic net returns t ech production phse re clculted s the difference between gross revenue per clf nd the opportunity cost of growing the clf nd reflect the bility of ech production phse to generte return on investment, i.e., mke profit. The finncil net returns re clculted s the difference between gross revenue per clf nd the ccumulted costs of growing the clf nd reflect the bility of ech production phse to generte csh flow. The mjor costs for wened clf re those necessry to support the cow enterprise. As indicted, only budgets for finncil costs were clculted through wening. The hy cost, $40/t, ws bsed on budget estimtes for hrvesting ($30/t) nd feeding ($10/t) excluding lbor. These costs included ownership costs for interest nd deprecition on the equipment. Lbor costs included in the budgets were bsed on ctul lbor for feeding nd clving s recorded by the University stff t GSL. We chrged lbor t the rte of $7.50/hr except clving lbor which ws chrged t time nd hlf since we believe clving to require more skilled lbor nd often occurs t night. No other lbor ws included in cow budgets since we ssumed tht other lbor would be similr between systems. Purchsed feeds such s protein supplement nd slt nd 2001 Nebrsk Beef Report Pge 10

11 minerl were chrged t ctul costs bsed on 1998 prices. Interest on the vlue of cows nd bulls ws chrged t 7.5%. Following Stndrdized Performnce Anlysis guidelines, replcement heifer costs were estimted from the net cost to produce wened clf. We used n initil selection rte of 20% of the heifer clves with 16% of these heifers ending up in the cow herd. We did not include the dditionl costs to tke the heifer from clf to cow sttus. Bsed on preliminry reserch, it ppers the first clf heifers cn be developed for similr costs in the two systems. Costs for ensuring tht the first clf heifer is bred for the second clf my be higher for the June system, but reserch is incomplete t this time. It is not likely tht costs for the second clf will be different enough between the two systems to lter the conclusions of this pper. Ech cow cost budget ws credited with cull income for sle of cull cows, bulls nd heifers minus deth loss. We ssumed the sme cull weight of 1,100 pounds for both (Mrch nd June) cow herds. Cull prices vried from yer to yer nd between systems since culls re usully vilble t different times of the yer in the two systems. Grzing costs were estimted t $4/cow/month when grzing uplnd nd $6/cow/month while grzing medow. These re finncil costs only nd cover such items s repir nd upkeep on fence nd wter nd operting costs for checking cttle. To properly grze medows, more fencing nd wter is required thn with uplnd. The costs do not include the vlue of the forge. Animl helth ws not gretly different between the two systems; however, we did include $15/ cow veterinry nd medicine costs in both systems. Costs beyond wening were bsed on the ctul feeds fed nd feeding lbor. Grss for June-born clves tht were summered on grss the second summer ws chrged t the rte of $0.50/hd/dy. This cost is intended to cover the costs of renting dditionl grss where the lndlord checks the clves nd tkes cre of ll psture nd wter mngement. Feedlot costs were ctul chrges from the University feedlot ner Med, Neb., Tble 1. Averge nnul costs for Mrch-born clf-fed nd June-born clf-fed nd yerling steers. June Mrch Clf-fed Yerling Production phse Clf-fed Rnge Medow Rnge Medow Economic costs/steer clf Cow cost/clf wened $252 $173 $178 $173 $178 Clf costs: wen to on grss or feedlot $404 $397 $417 $466 $487 Yerling costs: on grss to feedlot $543 $559 Feedlot costs $653 $666 $671 $751 $751 Finncil costs/steer clf Cow cost/clf wened $252 $173 $178 $173 $178 Clf costs: wen to on grss or feedlot $294 $219 $225 $283 $289 Yerling steer costs: wen to feedlot $382 $389 Feedlot costs: wen to slughter $580 $505 $511 $636 $643 Economic costs include the opportunity cost of the incoming niml, i.e., the vlue of the niml priced t mrket. Finncil costs include the ccumulted costs of producing the niml. Tble 2. Averge nnul net returns for Mrch-born clf-fed nd June-born clf-fed nd yerling steers. June Mrch Clf-fed Yerling Production phse Clf-fed Rnge Medow Rnge Medow Economic net returns/steer clf Clving to wening $86 $151 $161 $151 $161 Wening to on grss ($36) ($20) ($34) ($28) ($32) On grss to in feedlot ($45) ($62) In feedlot to slughter $27 ($38) ($45) $20 $34 Finncil net returns/steer clf Clving to wening $86 $151 $161 $151 $161 Wening to on grss $74 $158 $158 $156 $165 On grss to in feedlot $115 $108 In feedlot to slughter $100 $124 $117 $135 $141 which included $0.30/hd/dy yrdge chrge. The costs were bsed on 1998 rtion ingredient cost plus $1/cwt trucking chrge to nd from the feedlot. Results The economic nd finncil cost budgets re summrized in Tble 1. Through wening the costs for both the economic nd finncil budgets were treted the sme since there is no opportunity cost of n incoming niml t wening. The cost of producing June-born wened clf ws $74 to $79 lower per clf thn the cost of producing Mrch-born wened clf due to reduced hrvested forge nd feeding nd clving lbor expenses. The dditionl finncil costs to grow steer clf pst wening were nerly the sme for both the June- nd Mrch-born clf fed systems; therefore, the finncil cost dvntge remined with the June system through the feedlot. However, the post-wen economic costs for the Mrch born, clf-feds were slightly lower into the feedlot compred to June born clves bred on medow ($404/hd versus $417/hd) nd slightly higher thn June born clves bred on rnge (Tble 2). The economic nd finncil costs for June-born yerlings reflect the higher incoming niml vlues s well s the higher costs of finishing the clves s yerlings. The economic nd finncil net returns to the Mrch- nd June-born systems re summrized in Tble 2. When evluting the economic net (Continued on next pge) Pge Nebrsk Beef Report

12 returns, negtive vlue for phse of production indictes tht phse would not stnd lone s n enterprise without being subsidized by erlier or lter phses. The phse does not generte profit. Similrly, negtive finncil net return, though not experienced, would indicte tht growing steer clf to production phse would not generte positive csh flow. Selling June-born wened clf in Jnury from either the rnge- or medow-bred tretments provided $65 to $75 more net returns, on verge, thn Mrch-born wened clf sold in September/October. This difference is due to two effects. First, it cost less to produce June-born clf. Second, the price received for June born clves sold in Jnury verged nerly $10/cwt higher (rel prices) compred to the price received for the Mrch-born clf sold in September/October. The price differentil is rel effect of chnging systems nd must be considered if chnges such s this re contemplted by ny producer. It comes from typiclly higher sesonl price in Jnury compred to September/October nd the fct tht the June-born clves re lighter so the price slide lso gives these clves price dvntge. The net effect is tht the gross sle vlue received for June-born clf sold in Jnury is bout the sme s Mrch-born clf sold in the September/October time frme. The post-wen economic net returns indicte the June system is only profitble if the wened clf is finished s yerling nd the Mrch system is profitble if the wened clf is finished in the feedlot. From the finncil (csh flow) stndpoint, the June system lwys generted higher net returns thn the Mrch system. The gretest finncil net returns were for the June-born yerling prior to being put on grss. 1 Gordon Crriker, former reserch nlyst; Dick Clrk, professor, Agriculturl Economics; Don Adms, professor, Animl Science; Russ Sndburg, reserch technologist; West Centrl Reserch nd Extension Center, North Pltte. June Versus Mrch Clving for the Nebrsk Sndhills: Economic Risk Anlysis Gordon Crriker Dick Clrk Don Adms Russ Sndberg 1 A June clving system cn be more profitble thn Mrch clving system without incresing economic risk. Summry Price risk nlysis of economic nd finncil net returns from June nd Mrch clving systems ws used to rnk nd identify preferred production/sle strtegies ccording to risk preferences of producers. Anlysis of economic net returns identified selling June-born steer t wening from the breeding on medow (medow-bred) tretment s preferred strtegy regrdless of risk preferences. Post-wening, selling June-born finished yerling steer from the medow-bred tretment ws rnked highest. Anlysis of finncil net returns identified selling June-born yerling steer from the medow-bred tretment prior to summer grzing s preferred for ll but those strongly risk verse; selling June-born steer from the medow-bred tretment t wening rnked second. Introduction Production griculture is subject to severl sources of economic risk: output price, yield, nd input nd cost. A simple comprison of verge net returns from lterntive production strtegies overlooks risk. Comprison of the Juneborn clving system to the trditionl Mrch-born clving system lso should include n evlution of the economic risks involved. The objectives of this reserch were to: 1) identify the risk efficient (preferred) set of production strtegies in the two clving systems bsed on the economic nd finncil net returns; nd 2) rnk the production stges in order of risk preference bsed on the economic nd finncil net returns distributions. We hypothesized tht the production stges in the June system would be preferred over the sme stges in the Mrch system. Procedure Economic nd finncil net returns distributions were generted for ech production stge for both the Mrch nd June clving systems using verge input levels nd niml weights, 1998 input costs nd rel (infltion djusted) prices received from 1992 through Thus, the vrition in net returns reported here is due strictly to vrition in cttle prices. Economic net returns indicte the bility of n individul stge of production to generte n economic profit, i.e., the bility to stnd lone s seprte enterprise without being subsidized by n erlier or lter production stge. Finncil net returns indicte whether producing to stge of production will generte positive csh flow. The 15 numbered sles strtegies (Tble 1) correspond with the stges of production nd the lterntive systems. For exmple, number 7 refers to selling 2001 Nebrsk Beef Report Pge 12

13 Tble 1. Number identifiers for production/sell strtegies for Mrch nd June clving systems. June Production stge/ Mrch Clf feds Yerlings Sell t: Clf feds Rnge Medow Rnge Medow Wening Yerling clf onto grss Into feedlot Slughter wenling clf born in June nd bred on the medow. Risk nlysis considers not only the level of net returns from ll strtegies, but lso the vrition in those returns. Rnking strtegies ccording to risk is not n esy tsk unless some strtegies totlly dominte ll others. A dominting strtegy would hve higher net returns under ll price situtions. Generlized stochstic dominnce (GSD) nlysis of the economic nd finncil net returns distributions is tool tht cn identify the preferred sles strtegies nd cn rnk ll strtegies ccording to the risk chrcteristics of the producers. GSD is the tool we chose to rnk the finncil nd economic net returns. GSD nlysis does not mke priori ssumptions regrding the net returns distributions or the risk ttitude of decision mkers.. The nlysis llows for the rnking of lterntive strtegies over selected risk ttitudes of the decision mker. GSD hs been frequently used to rnk crop rottions, crop vrieties, pest nd fertilizer mngement lterntives nd other griculturl risk mngement strtegies. First- nd second-degree stochstic Tble 2. Stochstic dominnce nlysis rnkings of economic net returns from Mrch nd June clving systems. Preference Rnkings Criteri More preferred " Less preferred FSD 7,4,1,15,12,3,5,10,13,6,9,2,8,11,14 SSD 7,4,1,15,3,12,5,10,2,8,13,11,6,9,14 SDRF Approximte Risk Attitude Strongly Risk Preferring 7,4,1,15,6,12,3,9,13,10,5,11,8,14,2 Modertely Risk Preferring 7,4,1,15,3,12,6,5,10,9,13,8,11,2,14 Slightly Risk Preferring 7,4,1,15,3,12,5,10,13,6,8,2,9,11,14 Risk Neutrl 7,4,1,15,3,12,5,10,8,13,6,2,9,11,14 Slightly Risk Averse 7,4,1,15,3,12,5,10,8,13,2,6,11,9,14 Modertely Risk Averse 7,4,1,15,3,12,5,2,8,10,11,13,6,14,9 Strongly Risk Averse 7,4,1,15,3,12,5,2,8,10,11,13,14,6,9 Refer to Tble 1 for strtegy codes. Bolded, itlicized strtegies re in the most preferred set. Tble 3.Stochstic dominnce nlysis rnkings of finncil net returns from Mrch nd June clving systems. Preference Rnkings Criteri More preferred " Less preferred FSD 15,6,7,8,13,5,10,4,9,12,14,11,3,1,2 SSD 6,8,15,7,13,5,12,9,4,14,11,10,3,1,2 SDRF Approximte Risk Attitude Strongly Risk Preferring 13,5,7,8,10,4,15,12,6,9,11,3,14,1,2 Modertely Risk Preferring 13,7,5,8,10,4,15,12,6,9,11,3,14,1,2 Slightly Risk Preferring 13,7,5,8,10,4,15,12,6,9,11,14,3,1,2 Risk Neutrl 13,7,10,5,8,4,15,12,6,9,11,14,3,1,2 Slightly Risk Averse 13,7,8,5,10,4,15,12,6,9,11,14,3,1,2 Modertely Risk Averse 13,7,8,15,6,5,12,9,4,10,11,14,3,1,2 Strongly Risk Averse 6,9,15,12,7,8,4,5,13,14,11,3,10,1,2 Refer to Tble 1 for strtegy codes. Bolded, itlicized strtegies re in the most preferred set. dominnce re specil cses of GSD. First-degree stochstic dominnce (FSD) ssumes only tht the decision mker prefers more to less, with no ssumption bout the decision mker s risk ttitude. Second-degree stochstic dominnce (SSD) ssumes the decision mker prefers more to less nd is risk verse. FSD nd SSD re limited in their bility to discriminte between risky lterntives due to the nture of the underlying distributions being compred. FSD cn only choose between two lterntives when the net returns for ll situtions for one lterntive either re equl to or greter thn net returns for the other lterntive. SSD cn rnk two lterntives when the net returns over ll situtions exceed those of the other t ll points in the cumultive probbility distribution. This criterion cnnot rnk two lterntives where cumultive probbility of lterntive b s net returns exceed lterntive s t low levels of probbility nd then the cumultive probbility of lterntive s net returns exceed b s t higher levels of probbility. The cumultive probbility of level of net returns is the probbility tht net returns re equl to or less thn certin level. Since FSD nd SSD lone re limited, we hve used stochstic dominnce with respect to function (SDRF), which gives more power for rnking lterntives, with the rnkings depending on the risk ttitude of the decision mker. SDRF is the most generlized decision criterion ssocited with GSD nlysis. Results The results of the GSD nlysis of economic nd finncil net returns re presented in Tbles 2 nd 3, respectively. FSD, SSD, nd SDRF nlyses of the economic net returns (Tble 2) identify sle t wening of June-born clf feds from the medow breeding tretment (strtegy 7) s economiclly preferred. All tht is necessry to ssume bout the decision mker is tht he/she prefers more to less since strtegy 7 ws the dominnt strtegy with FSD. If our gol is to only find the dominnt strtegy for economic returns, then FSD ws dequte. Notice (Continued on next pge) Pge Nebrsk Beef Report

14 tht specifying the risk ttitude mde no difference in the preferred set. Sle t wening of June-born clf fed from the rnge breeding tretment (strtegy 4) ws rnked second followed by sle t wening of Mrch-born clf fed (strtegy 1). However, if we re interested in the rnking of ll lterntives, then the risk preference of the decision mker becomes importnt which cn be seen by compring the rnkings fter the top four strtegies s the risk ttitude chnges. When the nlysis turns to the finncil net returns, FSD nd SSD cnnot rnk single lterntives. FSD nd SSD nlysis of the finncil net returns identified six strtegies s ll in the risk efficient set (eqully preferred; Tble 3). The numbers in bold itlics note the six eqully preferred strtegies. However, the more discriminting SDRF nlysis identifies sle of yerling clf from the medow breeding tretment prior to summer grzing (strtegy 13) s the risk efficient (preferred) strtegy for strongly risk preferring to slightly risk verse producers. Modertely risk verse producers would be indifferent between five lterntives, ll in the June clving system. The preferred strtegy for strongly risk verse producers is the sle t slughter of June-born clf fed from the rnge breeding tretment (strtegy 6). With some knowledge of decision mker s risk ttitudes, SDRF ws ble to rnk the 15 strtegies in most cses. Regrdless of the risk ttitude, SDRF nlysis of the finncil net returns rnks the Mrch clving system strtegies low nd often lest preferred. Recll tht this nlysis considered only risk due to cttle prices. There my be other risks tht hve not occurred with our reserch tht should be considered. If future reserch delinetes possible other risks, they will be incorported into the nlysis. 1 Gordon Crriker, former reserch nlyst; Dick Clrk, professor, Agriculturl Economics; Don Adms, professor, Animl Science; Russ Sndberg, reserch technologist, West Centrl Reserch nd Extension Center, North Pltte. Protein Supplements nd Performnce of Cows nd Clves in June-Clving Production Systems Ameli Hopkin Don Adms Terry Klopfenstein Todd Milton Dick Clrk 1 June-born clves grzed through the winter on cows fed protein supplement. Winter gin nd summer protein supplement ffected gin of yerling steers on summer grss nd in the feedlot. Summry Lctting, June-clving cows tht received protein supplement Jnury through Mrch mintined lower body condition thn dry June cows. Dry, nonsupplemented cows lost more body condition compred to dry, supplemented cows over tht sme time period. Juneborn steers wintered t low rte of gin (.4 lb/dy) hd higher dily gins on sub-irrigted medow during My thn June born steers wintered t higher rte of gin (1.6 lb/dy). Supplementl protein fed during summer grzing on rnge incresed dily gins for steers wintered t both high nd low gins compred to non-supplemented steers. Introduction A primry fctor in determining economic efficiency in the beef cttle industry is feed cost. A June clving system ws developed t the University of Nebrsk Gudmundsen Sndhills Lbortory (GSL) to mtch the nutrient requirements of the cow to the nutrients vilble in the forge nd to reduce the mount of hrvested or purchsed feeds tht re typiclly fed in Februry-Mrch clving systems. The need for protein supplement for grzing winter rnge fter wening in Jnury hs not been determined in the June clving system. Although nutrient content of the forge is low, nutrient requirements of dry cow in the middle third of pregnncy lso re low; therefore, supplementl protein my not be needed. When yerlings re integrted into the June-clving system, hrvested nd/or purchsed feed nd lbor ssocited with feeding the clf fter wening from Jnury to grss in My might be decresed by extending the grzing seson of the clf through the 2001 Nebrsk Beef Report Pge 14

15 winter. Grzing by the clf through the winter my be possible by leving the clf with the cow from Jnury to April, provided the cow is fed supplementl protein. The effect of rte of winter gin on summer gins of yerlings from June-clving systems nd the effect of supplementl protein on summer dily gin of yerling steers from Juneclving system hve not been determined. Our objectives were to evlute: 1) the efficcy of extending grzing of June-clving cows nd clves through winter, 2) effects of supplementl protein on dry June-clving cows grzing winter rnge, nd 3) response of Juneborn yerling steers grzing summer rnge to supplementl protein. Procedure Winter grzing for dry nd lctting June clving cows Yer 1. June-clving cows (95 hed) were llotted eqully to three winter grzing tretments: 1) Lctting cows with protein supplement (Lct-S), 2) Dry cows with protein supplement (Dry-S), nd 3) Dry cows without protein supplement (Dry-NS). The winter grzing study begn Jn. 6, 1999 nd ended Mrch 30, On Jn. 6, 1999, clves from cows in tretments 2 nd 3 were wened. All heifer clves nd one-hlf of ll steer clves were wened on Jn. 6. Steer clves not wened on Jn. 6 nd their dms were ssigned to tretment 1. Supplements were individully fed three times weekly to cows in tretments 1 nd 2. Supplements were formulted to meet degrdble intke protein (DIP) nd undegrdble intke protein (UIP) requirements of dry nd lctting cows. Clves in tretment 1 were wened on Mrch 31. Body weight, body condition score (BCS), nd pregnncy were recorded on ll cows. (Tble 2). Yer 2. The winter grzing study ws conducted from Jn. 6, 2000 through Mrch 29, 2000 during the second yer. June clving cows (n=118) were split mong the three tretments nd ll procedures were the sme s in yer 1. June-born yerling steers Yer 1. June-born steers (n=62) were llotted to two rtes of gin during winter nd two protein tretments during summer grzing in 2 x 2 fctoril rrngement on Jn. 6, Rtes of gin during winter were: 1) high gin nd 2) low gin. Protein tretments during summer grzing on rnge were: 1) supplementl protein nd 2) no supplementl protein. June born steers on high gin were wened Jn. 6, 1999 nd were fed whet middlings t 2.8 lb/hed/dy nd grss hy t 11.2 lb/hed/dy to gin 1.6 lb/dy during winter. Low gin steers nursed the cows on rnge Jn. 6 to Mrch 30, 1999 (tretment 1 of the cow study) nd gined.4 lb/dy. Steers wintered t high nd low gin grzed subirrigted medow from April 30 to My 31 nd uplnd Sndhills rnge from June 1 to Sept. 9. One-hlf of the steers on both low nd high winter gin tretments were fed protein supplement on rnge from June 7 to Sept. 8, Tble 1. Composition of protein supplement fed to June-born steers grzing uplnd Sndhills rnge. Ingredient % of supplement Treted Soyben Mel 76.5 Fether Mel 18.8 Molsses 3.7 Pellet Binder 1.0 Steers on the supplement tretment were individully fed 2.9 lb of supplementl protein (Tble 1) three times weekly. Body weight ws recorded t the beginning nd/or end of ech grzing period through the winter nd summer nd verge dily gin ws clculted. Steers were finished t the University of Nebrsk feedlot t Med, Neb. Feedlot nd crcss dt re not presented in this pper. Results Winter grzing of dry nd lctting June clving cows Becuse there were no tretment by yer interctions (P >.10), yer effects were pooled cross tretments. Cow body weight did not differ between the Lct-S nd Dry-S cows nor the Dry-S nd Dry- NS cows. Protein supplement ppers to be importnt for dry cows to mintin condition while grzing dormnt winter rnge, s shown by the lower (P <.01) BCS of Dry-NS cows (4.4) compred to Dry-S cows (4.7) on Mrch 30. Lctting cows receiving protein supplement hd lower BCS t the end of winter grzing on Mrch 30 thn dry cows receiving protein supplement (Tble 2; P <.01). Body weight (1226 lb) nd BCS (5.4) were similr (P >.10) cross ll tretments t preclving in June nd prebreeding in September for yer 1. It is interesting to note tht lthough Tble 2. Lest squres mens for cow body weight nd body condition score for lctting cows receiving protein supplement (Lct-S), dry, supplemented cows (Dry-S), nd dry, nonsupplemented cows (Dry-NS) grzing winter rnge in 1999 nd Item Lct-S Dry-S Dry-NS Contrst Body Weight, lb Jn. 6, On Tril ns b Mr. 30, Off Tril ns Body Condition Score Jn. 6, On Tril ns Mr. 30, Off Tril Lct-S vs. Dry-S** Dry-S vs. Dry-NS** All tretment x yer interctions were non-significnt (P>.10). b ns = Non-significnt P >.10. ** Significnt P <.01 (Continued on next pge) Pge Nebrsk Beef Report

16 vrition in BCS occurred between the three tretments on Mrch 30, BCS for ll tretments ws similr t preclving nd prebreeding. Percentges of cows pregnnt for yer 1 on Jnury 6, 2000 were 96.2% for Lct-S cows; 89.7% for Dry-S cows; nd 88.0% for Dry-NS cows. Pregnncy dt re considered insufficient to drw conclusions until pregnncy dt re vilble for yer 2. Yerling steers No rte of winter gin by protein supplement interctions occurred (P >.10). Steers wintered t high gin were 57 lb hevier (P <.01) nd 24 lb hevier (P <.10) thn steers wintered t low gin on Mrch 30 nd on September 14, respectively. June-born steers wintered t low rte of gin hd dily gins.7 lb greter (P <.01) thn steers wintered t high gin while grzing subirrigted medow in My (Tble 3). Protein supplement incresed dily gin of steers by.4 lb/dy compred to non- Tble 3. Body weight nd verge dily gin (ADG) of June-born steers wintered t low (.4 lb/dy) nd high (1.6 lb/dy) rtes of winter gin, grzing sub-irrigted medow without protein supplement (supp.) or rnge with or without protein supplement during Winter gin Protein supplement Item Low b High P c No supp. Supp. P d Body weight, lb Apr. 30, On medow ** ns My 28, On rnge ** ns Sep.14, Off grss ** ADG, lb Apr My 28, Medow ** ns My 29 - Sep. 14, Rnge ** ** Apr Sep. 14, Combined ** ** Interctions between rte of winter gin nd supplement were non-significnt (P>.05). b Clves in this tretment were nursing cows in tretment 1 of cow study. c Low vs. high, ** = P <.01, + = P <.10. d No supp. vs. Supp., ns = non-significnt, ** = P <.01. supplemented steers while grzing summer rnge. Wintering June-clving cows with their clves on rnge Jnury through Mrch my be prcticl method to overwinter clves in yerling systems if cows re fed protein supplement. Dily gin during winter nd protein supplement during summer grzing ffect dily gins nd body weights t the end of summer grzing. 1 Ameli Hopkin, grdute student Animl Science; Don Adms, professor Animl Science, West Centrl Reserch nd Extension Center, North Pltte; Terry Klopfenstein, professor Animl Science; Todd Milton, ssistnt professor, Lincoln; nd Dick Clrk, professor Agriculturl Economics, West Centrl Reserch nd Extension Center, North Pltte. Performnce nd Economics of Winter Supplementing Pregnnt Heifers Bsed on the Metbolizble Protein System Trey Ptterson Don Adms Terry Klopfenstein Richrd Clrk Burke Teichert 1 Supplementing pregnnt heifers grzing winter rnge to meet metbolizble protein versus crude protein requirements my improve two-yer-old pregnncy nd profitbility. Summry In nd in , pregnnt, Mrch-clving heifers (2,375 hed) t two loctions of rnch in Nebrsk were used to evlute the production nd economic responses of winter supplementtion (September to Februry) to meet metbolizble protein or CP requirements. Net present vlue ws used to determine the economic benefits of supplement tretments. In , metbolizble protein heifers hd higher pregnncy rtes nd expected profitbility thn CP heifers t one of two loctions. In , metbolizble protein heifers hd higher pregnncy rtes nd expected profitbility t both loctions. Introduction For young cows to recover development costs, they must sty in production for multiple yers. Economicl nutrition progrms tht fcilitte improved 2-yer-old pregnncy rte hve the potentil to improve expected lifetime profitbility. The undegrdble intke protein (UIP) content of grzed winter forge in the Sndhills of Nebrsk is low (1997 Nebrsk Beef Report, pp. 3-5). Microbil crude protein (MCP) production 2001 Nebrsk Beef Report Pge 16

17 often is indequte to meet the metbolizble protein (MP) requirement of growing heifers, resulting in need for supplementl UIP. Providing dditionl MP to pregnnt heifers decresed winter body weight (BW) loss in some situtions (2000 Nebrsk Beef Report, pp. 7-10). The objective of the study ws to document differences in reproductive performnce when heifers re supplemented to meet MP rther thn CP requirements. We hypothesized supplementing to meet MP requirements would improve 2-yer-old pregnncy nd lifetime vlue of the bred heifer. Procedure In (1156 hed; 772 lb) nd (1219 hed; 813 lb), pregnnt heifers t two loctions of commercil rnch in the Nebrsk Sndhills were used following breeding s yerlings through pregnncy testing s 2-yerolds. The verge clving dte ws Mrch 25 of ech yer. Heifers were llotted rndomly to one of two tretments (pproximtely 300 hed/tretment) ech yer t ech loction (loctions ner Ashby nd Whitmn). Heifers received supplements while grzing fll-winter uplnd rnge nd medow from mid- September to mid-februry of ech yer. Tretments were: 1) supplementtion to meet MP requirements (MPR) or 2) supplementtion to meet CP requirements (CPR). Fether mel ws used for the UIP source in the MPR supplement (Tble 1), with the supplement composed of 53% CP nd 27% UIP (DM bsis). The CPR supplement ws composed of 51% CP nd 13% UIP. The CPR supplement ws fed t the rte of.89 lb/dy (DM) throughout the tril, supplying 53 grms of UIP/dy. The MPR supplement feeding rte incresed grdully from.70 lb/dy in October to 1.6 lb/dy in Februry, supplying 86 grms UIP/dy in October, 120 grms UIP/dy in November, December, nd Jnury, 135 grms UIP/dy in erly Februry, nd 203 g UIP/dy fter Febr. 15. Supplements were fed to tretment groups three times weekly s rnge cubes. Medow hy (7-9% CP) ws fed t the discretion of the mnger t ech loction in ech yer. Hy ws typiclly fed t rte of 4.5 lb/dy (DM bsis) strting in mid- to lte December nd incresed to bout 18 lb/dy in Februry s heifers pproched prturition. Heifers from ech tretment t ech loction were mnged in one group from mid- Februry to October of ech yer. Approximtely 18 lb/dy medow hy (DM bsis) nd rnge were vilble mid-februry (no supplement) until clving. After clving, pproximtely 24 lb of medow hy nd 4 lb of lflf hy (DM bsis) were fed dily until vilble grzing. Heifers were exposed to mix of mture nd yerling bulls for 90 dys beginning June 10 of ech yer. In , heifers were individully weighed nd ssigned body condition score (BCS) on Sept. 15 nd 16, Febr. 27 nd 28, nd on Oct. 21 nd 22 (one dy for ech loction). Wening weights were tken on clves on Aug. 14 t Whitmn nd Sept. 3 t Ashby. Pregnncy ws determined by plption on Oct. 21 nd 22. In , heifers were weighed nd BCS on Sept. 16 nd 17, Febr. 16 nd 18, nd Oct. 25 nd 27. Wening weights were tken on clves on Aug. 19 t Whitmn nd Sept. 2 t Ashby. Pregnncy ws determined by plption on Oct. 25 nd 27. Budgets were set up strting with n rbitrry 100 bred heifers both in 1998 nd 1999, corresponding to the yers tht supplement tretments were pplied. Budgets were consistent with mngement where the experiment ws conducted, nd ctul dt from the opertion were used to determine pregnncy, wening, cull, nd deth rtes, nnul cow costs, nd the weight of cttle mrketed (either clves or cull femles). All costs were inflted by 2.0% per yer. Since costs nd performnce were similr cross loctions, one set of costs nd performnce dt were used for both loctions within ech yer. Revenue ws clculted using mrket dt for 1998 nd 1999 (Crop nd Livestock Prices for Nebrsk, 1998), nd projected prices for yer Mrket prices for yers 2001 through ge 15 of the cows were estimted by historicl dt reported from 1985 to Annul net csh flow ws determined for the originl set of 100 femles for ech yer up to when the cttle turned 15 yers old. The inventory of heifers chnged ech yer within ech budget, s it ws reduced by the number of cows sold or ded. All cows remining t ge 15 were considered to be sold. Since the CPR tretment ws the conventionl supplementtion protocol for this opertion, the 2-yer-old pregnncy rte for the CPR tretment ws used s the bse for ech loction within ech yer. Pregnncy rte of 2-yer-old cows from the MPR tretment then ws used in the budget to determine chnge in lifetime csh flow. Effects of tretments on 2-yer-old pregnncy were ssumed to not ffect future production prmeters. Net present vlue (NPV) of the bred heifers (2-yer-old production yer) ws determined from the budgets using the formul: NPV = E1/(1+i) 1 + E2/(1 + i) En /(1 + i) n, where E is net csh flow in ech yer 1 through n (n = 15 in this cse), nd i is the discount rte. A discount rte of 7.0% ws used for ll clcultions, nd this ws ssumed to be rel rte of discount. The NPV of bred heifers ws clculted for both tretments t ech loction within ech yer. The NPV for the group ws divided by the originl 100 hed to obtin NPV on per hed bsis. The MPR tretment cost more thn CPR in ($2.71 nd $3.33 difference in totl supplement costs per hed t Ashby nd Whitmn, respectively), nd in ($0.58 nd $0.59 t Ashby nd Whitmn, respectively). The different tretment costs were ssocited with costs of ingredients (Tble 1) (Continued on next pge) Tble 1. Composition of supplements fed to heifers grzing winter sndhills rnge (% of DM). Ingredient MPR CPR Cottonseed Mel 58.8 Fether Mel 40.2 Soyben Mel 17.8 Sunflower Mel Whet Middlings 26.2 Distillers Grins 3.4 Molsses (Cne) Ure 2.8 Minerls/Vitmins Supplements were provided s rnge cubes fed 3 times weekly. MPR: designed to meet the metbolizble protein requirement; CPR: designed s conventionl protein supplement. Pge Nebrsk Beef Report

18 nd the mount of supplement fed. The difference between MPR nd CPR supplement costs ws lower in , becuse the tril ended erlier in Februry before the scheduled increse in the mount of MPR to be fed. Results No tretment interctions or tretment effects on cow BW or BCS chnge between September nd Februry, Februry nd October, or September nd October were observed (Tble 2; P >.15). Clf wening weights were similr between tretments. A tretment yer loction interction for pregnncy rte (P =.07) ws present. Therefore, pregnncy rte ws nlyzed within loction of ech yer (Tble 3). In , both MPR nd CPR heifers t Ashby hd pregnncy rte of 95%. At Whitmn in , however, MPR heifers hd higher pregnncy rte (P =.01; 84%) thn CPR heifers (75%). In , the MPR heifers hd higher pregnncy rte (P =.01; 95%) thn CPR heifers (88%) t Ashby, nd MPR heifers tended to hve higher pregnncy rte (P =.15; 89%) thn CPR heifers (85%) t Whitmn. The 95% pregnncy rte of both tretments t Ashby in indicte supplementl UIP bove the mount in the CP blnced supplement ws not necessry. Bsed on BW chnge, BCS chnge, nd pregnncy rte t Ashby in , it ppers energy intke ws not mrkedly restricted to the heifers. Since MCP production is function of energy intke, higher energy intkes llow more MCP production nd less need for supplementl UIP. The effects of yer on fll-winter diet qulity in the Nebrsk Sndhills hve been documented (1998 Nebrsk Beef Report, pp ). An incresed diet qulity nd/or forge intke t Ashby in potentilly could explin the lck of response to supplementl UIP. In the situtions in this study where pregnncy rte ws improved by supplementing to meet MP requirements, BCS loss over the winter ws greter thn.5 units. Ptterson et l. (2000 Nebrsk Beef Report, pp. 7-10) reported supplementing to meet MP versus CP Tble 2. Body weight (BW), body condition score (BCS), nd clf wening weight of heifers supplemented to meet metbolizble protein requirements (MPR) or CP requirements (CPR) cross two loctions nd two yers ( nd ) in the Nebrsk Sndhills. Item MPR CPR SEM b Sept. BW, lb Feb., BW, lb Oct. BW, lb BW Chnge, Sept.-Feb., lb BW Chnge, Feb.-Oct., lb BW Chnge, Sept.-Oct., lb BCS, Sept <0.1 BCS, Feb BCS, Oct BCS Chnge, Sept.-Feb BCS Chnge, Feb.-Oct BCS Chnge, Sept.-Oct Clf Wening Weight, lb heifers were group fed supplement in tretment groups (pproximtely 300 heifers per tretment t ech loction during ech yer). b Stndrd error of the men; n = 8. Tble 3. Pregnncy rte of heifers supplemented to meet metbolizble protein requirements (MPR) or CP requirements (CPR) t two loctions in the Nebrsk Sndhills in nd Ashby Whitmn b Item MPR CPR MPR CPR , % c , % d n = 531 in ; n = 527 in b n = 501 in ; n = 560 in c Tretments different t Whitmn (P =.01). d Tretments different t Ashby (P =.01) nd Whitmn (P =.15). Tble 4. Net present vlue (NPV) of bred heifers when two-yer-old pregnncy rte ws ffected by supplementing the heifers during the winter prior to clving to meet metbolizble protein requirements (MPR) or crude protein requirements (CPR) Item Ashby Whitmn Ashby Whitmn MPR NPV, $/hd CPR NPV, $/hd Difference, $/hd b Return, $/hd c Supplements fed from September to Februry ech yer. b Difference in NPV between MPR nd CPR within loction nd yer. c Advntge of MPR tretment in NPV fter dditionl supplement cost of tht tretment ws subtrcted. requirements improved heifer BW gin over the winter in one of two experiments. The uthors reported substntil BCS losses (-1.5 BCS from October to Februry) in the study where response to supplementing to meet MP requirements occurred. Energy intke cn become low in some situtions (2000 Nebrsk Beef Report, pp. 7-10), nd energy limits heifer performnce during the winter insted of MP. The increse in pregnncy rte in MPR compred to CPR heifers without improved BW or BCS chnge overwinter ws not expected. However, similr responses hve been reported with ft supplementtion during gesttion. The response to ft supplementtion hs been ssocited with ltered hormone profiles. Supplementl UIP post-prtum lters endocrine profiles in 2-yer-old heifers. Supplementing UIP 2001 Nebrsk Beef Report Pge 18

19 to heifers during gesttion my cuse post-prtum physiologicl chnges in the heifer tht positively influence re-breeding performnce. It is importnt to note effects of gesttionl UIP supplementtion occurred even though supplements were not fed immeditely before or fter clving. Although heifers strted clving in erly Mrch, the lst dy to feed the tretment supplements ws 25 nd 35 dys before the verge clving dte in nd , respectively. The 1996 NRC equtions predicted the medow hy nd rnge diet offered during this time ws deficient in MP (60 to 100 grms per dy). Metbolizble protein requirements increse exponentilly in the three weeks before clving. Although it is surprising tht reproduction ws positively ffected without supplementtion dys before clving, it is possible tht greter improvements in 2-yer-old pregnncy would hve been noticed hd UIP been supplemented through the clving seson. The NRC predicted tht cttle were dequte in MP fter clving. The NPV of heifers in ech tretment group t ech loction during ech yer re shown in Tble 4. As expected, in ll cses where pregnncy ws improved by the MPR tretment (Tble 3), NPV ws higher for heifers in the MPR tretment. Since the MPR tretment ws more expensive, the dded costs ssocited with this supplement strtegy were subtrcted from the difference in NPV to determine the expected return on the tretment. Bsed on NPV figures for the dt, the MPR tretment cost the femles t Ashby $2.71 over their lifetime compred to the CPR group, but gined those t Whitmn $ In , the MPR tretment returned $29.84 nd $16.79 over CPR femles t Ashby nd Whitmn, respectively. The verge difference between tretments in NPV, $20.00 per hed, would bring substntil revenue to n opertion. The importnce of reproduction in young breeding femles to profitbility hs been demonstrted in previous studies. The heifers in question were only t pproximtely 67% of their mture BW t yerling pregnncy check time in the fll. The literture would indicte tht 65% of mture weight should be obtined before breeding the replcement heifer. Rther modest nutritionl inputs into these heifers prior to clving, despite their low BW, showed substntil improvements in profitbility in three out of four situtions. 1 Trey Ptterson, reserch technicin, Animl Science, Lincoln; Don Adms nd Richrd Clrk, professors, West Centrl Reserch nd Extension Center, North Pltte; Terry Klopfenstein, professor, Animl Science, Lincoln, Burke Teichert, Rex Rnch, Ashby, NE. Forge Intke nd Nutrient Blnce of Heifers Grzing Sndhills Winter Rnge Trey Ptterson Don Adms Terry Klopfenstein 1 Metbolizble protein is deficient in pregnnt heifers grzing winter rnge. Energy my be first limiting if grzed forge intke is less thn 2.0% of body weight. Summry Two experiments with pregnnt heifers grzing winter rnge investigted effects of supplementtion to meet metbolizble protein versus CP requirements. Supplements were fed from October to Februry, nd hy ws fed in Jnury nd Februry of the second experiment. Supplementtion to meet metbolizble protein requirements decresed weight loss in one experiment. Winter hy feeding reduced weight loss nd body condition loss compred to no hy feeding. Forge intke declined from 2.1% of body weight in November to 1.3% in Februry. Metbolizble protein ws deficient when nimls were supplemented to meet CP requirements. Supplementtion to meet metbolizble protein requirements my improve performnce when energy intke is not deficient. Introduction Pregnnt, spring-clving heifers hve n elevted requirement for metbolizble protein (MP) during the winter, nd this requirement increses exponentilly s heifers pproch clving. Due to low energy nd undegrdble intke protein (UIP) content, the MP vlue of winter sndhills rnge is low. The result is n MP deficiency in the heifer. Supplementtion with protein sources high in UIP my llevite this deficiency. A study ws conducted t commercil opertion to determine effects of supplements fed over the winter to meet MP or CP requirements of pregnnt heifers. Metbolizble protein ws blnced with fether mel-bsed supplement. Supplementtion to meet MP requirements improved subsequent 2-yer-old pregnncy (2001 Nebrsk Beef Report). However, it could not be determined from the experiment if MP requirements were met by the supplement strtegy. In ddition, prediction of forge intke over the winter ws difficult due to little published dt on heifers grzing Nebrsk Sndhills winter rnge. Therefore, two experiments were conducted to evlute the effect of supplementing heifers to meet MP (Continued on next pge) Pge Nebrsk Beef Report

20 requirements versus CP requirements on weight nd body condition score chnge, forge intke, nd nutrient blnce. The performnce results were published in the 2000 Nebrsk Report pp Complete intke nd nutrient nlyses hve now been conducted. These nutrient blnce dt, combined with the performnce dt, cn be used to help define the supplementl requirements of the grzing heifer. Procedure Specific procedures re s described in the 2000 Nebrsk Beef Report pp Twelve pregnnt heifers in (Exp. 1) nd 18 heifers in (Exp. 2) were individully fed one of two protein supplements from mid- October to mid-februry while grzing sndhills rnge. In Exp. 1, two tretments were: 1) supplement designed to meet MP requirements (MPR) nd 2) conventionl protein supplement fed to meet CP requirements (CPR). No hy ws fed during the experiment. In Exp. 2, tretments were : 1) heifers supplemented to meet MP requirement nd fed hy (pproximtely 5 lb/dy) beginning in Jnury (MPR/Hy) 2) heifers supplemented with conventionl supplement nd fed hy beginning in Jnury (CPR/ Hy), nd 3) heifers supplemented to meet MP requirement nd offered no hy during the experiment (MPR/No Hy). Hy ws 8.4% CP nd ws determined to be 65% digestible in 5-dy in vivo tril with five steers. The MPR supplement (Tble 1) ws Tble 1. Composition of supplements fed to heifers in Experiments 1 nd 2 (% of DM). Ingredient MPR CPR Cottonseed Mel 58.8 Fether Mel 40.2 Soyben Mel 17.8 Sunflower Mel Whet Middlings 26.2 Distillers Grins 3.4 Molsses (Cne) Ure 2.8 Minerls/Vitmins Supplements were provided s rnge cubes fed 3 times weekly. MPR: designed to meet the metbolizble protein requirement; CPR: designed s conventionl protein supplement. composed of 53% CP nd 28% UIP (DM bsis). The CP supplement contined 51% CP nd 14% UIP. The CPR supplement ws fed t the rte of.89 lb/ dy (DM) throughout the tril, supplying 53 grms of UIP/dy. The MPR supplement feeding rte incresed grdully from.70 lb/dy in October to 1.6 lb/ dy in Februry, supplying 86 grms UIP/dy in October, 120 grms UIP/dy in November, December, nd Jnury, 135 grms UIP/dy in erly Februry, nd 203 g UIP/dy fter Februry 15. Intke mesurements were tken in six-dy periods beginning Nov. 10, Jn. 5, nd Febr. 9 in (Exp. 1). Intke mesurements were tken beginning Dec. 15 nd Febr. 18 in (Exp. 2). Time relese chromium boluses were used for determintion of fecl output in ech niml, nd predictions were vlidted with four steers using totl fecl collection. Diets were collected with esophgelly fistulted cows during ech intke period nd frozen for subsequent nlyses. Diet smples were freeze dried nd nlyzed for DM, OM, CP, UIP, IVDMD, nd in vitro orgnic mtter digestibility (IVOMD). Forge UIP ws determined by the mount of neutrl detergent insoluble protein remining fter 48- hour in situ incubtion. Forge orgnic mtter intke ws clculted by dividing fecl output from forge by forge indigestibility (1-IVOMD). Intke nd nutrient dt were used in the 1996 NRC model to determine nutrient blnces t the time intkes were conducted during ech experiment. Dt were modeled ssuming no effects of environmentl conditions on nutrient requirements. Microbil crude protein production ws ssumed to be 9.5% of TDN intke. Forge intke, CP, nd UIP were clculted on n OM bsis nd djusted to DM bsis ssuming 10% sh. In vitro dry mtter digestibility ws used for the forge TDN vlue. Results In Exp. 1, heifers supplemented to meet MP requirements lost less weight over the winter thn those supplemented to meet CP requirements (Tble 2; P =.04). All cttle lost substntil body condition over the course of the experiment (-1.5 BCS). As previously reported, cttle on the MPR tretment gined the weight dvntge erly in the fll, but both groups lost weight in Jnury nd Februry (2000 Nebrsk Beef Report, pp. 7-10). Grzed forge intke declined linerly (P <.01) from n verge of 21 lb (2.1% of body weight) in November Tble 2. Weight, BCS, nd forge intke (FI) of heifers grzing winter Sndhills rnge from October 1997 to Februry 1998 (Experiment 1). Item MPR CPR SD b Beginning wt, lb Finl wt, lb c Wt chnge, lb d Beginning BCS Finl BCS BCS chnge November FI, e,f lb % BW Jnury FI, e,f lb % BW Februry FI, e,f lb % BW MPR: heifers supplemented to meet metbolizble protein requirement; CPR: heifers supplemented with conventionl protein supplement. No hy fed during the experiment. b Stndrd devition, n = 12. c Tretments differ, P =.16. d Tretments differ, P =.04. e Dry mtter bsis. f Forge intke declined linerly over time (P =.0001) Nebrsk Beef Report Pge 20

21 Tble 3. Weight nd BCS of heifers grzing winter Sndhills rnge from October 1998 to Februry 1999 (Experiment 2). Item MPR/Hy CPR/Hy MPR/No Hy Stdev b Beginning wt, lb Finl wt, lb c Wt chnge, lb d Beginning BCS Finl BCS e BCS chnge f December FI, g,h lb % BW Februry FI, g,h lb % BW Februry FI + HI g,i lb % BW MPR/Hy: heifers supplemented to meet metbolizble protein requirements nd fed hy (verge 5 lb/ dy) in Jnury nd Februry; CPR/Hy: heifers supplemented with conventionl protein supplement nd fed hy in Jnury nd Februry; MPR/No Hy: heifers supplemented to meet metbolizble protein requirements nd fed no hy. b Stndrd devition, n = 18. c MPR/Hy nd CPR/Hy versus MPR/No Hy, P =.001. d MPR/Hy nd CPR/Hy versus MPS/No Hy, P = e MPR/Hy versus MPR/No Hy, P =.01; CPR/Hy versus MPR/No Hy, P =.10. f MPR/Hy versus MPR/No Hy, P =.10. g Dry mtter bsis.. h Forge intke declined linerly over time (P =.0001). i Forge intke + hy intke. Tble 4. Nutrient composition of diets collected in the Nebrsk Sndhills Nutrient November Jnury Februry December Februry CP, % DM UIP, % DM b DIP, % CP c IVDMD, % Diets collected from esophgelly fistulted cows. b Undegrdble intke protein; clculted from neutrl detergent insoluble CP remining fter 48 hour in situ incubtion. c Degrdble intke protein. to 13 lb (1.4% of body weight) in Februry. There were no differences between tretments in forge intke. In Exp. 2, heifers on the MPR/No hy tretment lost significntly more weight thn hy fed heifers (Tble 3; P <.01) nd more body condition thn MPR/Hy heifers (P =.10). Body weight loss ws greter thn reported in Experiment 1, but body condition loss ws not s severe. Grzed forge intke declined (P <.01) from 16 lb (1.8% of body weight) in December to 12 lb (1.3 % of body weight) in Februry. There were no differences in forge intke between tretments. Totl intke (forge + hy) ws greter for heifers fed hy thn those not fed hy (P <.01). The decline in intke over the winter ws more severe thn expected. Reduced digestibility, cold stress nd reduced forge vilbility cn cuse depression in forge intke over the winter. In Exp 1., IVDMD (Tble 4) decresed from 52.0% in November to 48.9% in Jnury, but then incresed to 49.4% in Februry. Reduced forge digestibility does not explin the drop in intke from Jnury to Februry. In Exp. 2, IVDMD dropped from 51.2% in December to 47.4% in Februry. The stocking rte in the psture where heifers grzed ws.70 AUM/cre during Exp. 1., with cumultive grzing pressure (totl AUM per ton of DM forge initilly vilble) of.59 AUM/ton. This would be considered moderte level of grzing for Nebrsk Sndhills winter rnge. It is unlikely tht forge ws limiting to the heifers during Exp. 1, especilly in Jnury. In Exp. 2, the psture ws stocked t 1.06 AUM/ cre (.83 AUM/ton cumultive grzing pressure). Forge potentilly becme limiting to the heifers in Exp. 2. However, the decline in grzed forge intke ws consistent cross yers. We hypothesize tht dvncing growth of the fetus nd fluids reduces rumen volume before clving. Heifers re typiclly t 85% of their mture weight t clving, but the spce cquired by the fetus nd fluids is similr to mture cow. Rumen fill limits intke of low qulity diets, nd reduced rumen volume reduces intke. This would be expected to hve the gretest effect during the lst month of gesttion, when the size of the fetus increses mrkedly. A reduction in grzed intke occurs t nutritionlly stressful time for the heifer, s protein nd energy requirements increse substntilly in the lst six weeks of gesttion. Feeding hy tht is more digestible nd cn exit the rumen fster will llow for higher totl intke. The nutrient composition of diets collected by esophgelly fistulted cows during both experiments is shown in Tble 4. Protein did not chnge mrkedly cross smpling time nd yer, but ppered to be higher in December of 1998 (6.1%) thn November of 1997 (5.3%). The undegrdble intke protein content of diets ws lower in (1.2% of DM) thn in (1.5% of DM). Less UIP in the forge cn contribute to MP deficiencies. However, the biologicl implictions of 0.3% UIP re smll. Due to both low UIP nd digestibility, winter Sndhills rnge hs low MP vlue. Metbolizble protein comes from two sources: 1) microbes leving the rumen (MCP), nd 2) intke protein tht escpes rumen degrdtion (UIP). Microbil crude protein is function of TDN intke, nd cn rnge from 8.0% to 13.0% of TDN. When rte of pssge is slow, MCP production is reduced, nd my be round 9.5%. The reduced MCP (Continued on next pge) Pge Nebrsk Beef Report

22 efficiency, long with the lower TDN intke, cretes reduction in MP coming from microbes. This is why cttle with high protein requirements, such s the heifer, cn experience n MP deficiency when grzing winter rnge. The nutrient blnces of the cttle during Experiments 1 nd 2 re shown in Tbles 5 nd 6, respectively. Degrdble intke protein ws dequte in ll diets during both experiments. However, energy (NEm) nd MP were not dequte in ll situtions. Heifers receiving the MPR supplement hd more positive NEm blnce thn CPR heifers in November of Exp. 1. This ws due to numericl increse in intke ssocited with tht tretment. MP ws deficient (-19 grms) to the CPR heifers in November, but ws 46 grms positive for MPR heifers. The energy nd protein blnce of the MPR heifers during November explins the incresed body weight gin observed for tht tretment during the fll. It ppers tht the MPR supplement ws formulted correctly to meet the MP requirements of the heifers in the fll. Energy nd MP were deficient in both groups of heifers in Jnury nd Februry of Exp. 1, explining the decline in gin nd body condition. Low energy intkes, combined with incresing niml requirements, cused n NEm deficiency reching -5.5 Mcl per dy in Februry. The low energy intkes reduced MP blnce in Jnury nd Februry s well, nd the MPR supplement did not supply enough UIP to meet the MP requirement. The MPR heifers were less deficient in MP thn CPR heifers. The MPR heifers were dequte in MP in December of Exp. 2 (Tble 6), while CPR heifers were 26 grms deficient. Energy intke ws slightly deficient in December for ll heifers. Unlike Exp 1, where NEm blnce ws 1.0 to 2.0 Mcl positive in the fll, energy ppered to be limiting body weight gin. Dry mtter intkes (forge + Tble 5. Nutrient blnce of heifers supplemented to meet metbolizble protein requirements (MPR) or crude protein requirements (CPR) in (Experiment 1). November Jnury Februry Item MPR CPR MPR CPR MPR CPR DM Intke b NEm blnce, Mcl MP supplied, g MP required, g MP blnce, g DIP supplied, g DIP required, g DIP blnce, g Clculted using 1996 NRC Model. b Totl intke. Tble 6. Nutrient blnce of heifers supplemented to meet metbolizble protein or crude protein requirements with hy feeding in Jnury nd Februry (MPR/Hy nd CPR/Hy, respectively) or supplemented to metbolizble protein requirements nd not fed hy (MPR/No Hy) in (Experiment 2). December Februry MPR CPR MPR MPR CPR MPR Item Hy Hy No Hy Hy Hy No Hy DM Intke b NEm blnce, Mcl MP supplied, g MP required, g MP blnce, g DIP supplied, g DIP required, g DIP blnce, g Clculted using 1996 NRC Model. b Totl intke. supplement) in December of Exp 2 were low compred to November intkes in Exp 1. The MPR/Hy heifers were dequte in MP in Februry, while the other tretment groups were negtive. However, energy ws deficient in ll tretments. Feeding hy helped reduce the energy deficiency in Februry noted in heifers not fed hy. When energy intke is dequte to meet the NEm requirement of pregnnt heifers, the heifers pper to respond to UIP supplementtion. Conventionl supplements, such s the CPR supplement, do not supply dequte UIP to the pregnnt heifer. This is true even when 5 lb of high qulity hy re fed. However, the energy requirements of the spring clving heifer re high over the winter. Grzed forge intke needs to be over 2.0% of body weight for energy requirements to be met. In the Nebrsk Sndhills, grzed forge intke will not supply dequte energy for Mrch clving heifers in Jnury nd Februry. Blncing supplements to meet MP requirements cn be n effective mngement strtegy if energy requirements re met. 1 Trey Ptterson, reserch technicin; Don Adms, professor, West Centrl Reserch nd Extension Center, North Pltte; Terry Klopfenstein, professor, Animl Science, Lincoln Nebrsk Beef Report Pge 22

23 Summer Grzing nd Fll Grzing Pressure Effects on Protein Content nd Digestibility of Fll Rnge Diets Trey Ptterson Terry Klopfenstein Don Adms Wlter Schcht Ptrick Reece Jcki Musgrve Amy Herron 1 Protein content nd digestibility of fll cow diets my decline with incresing levels of fll grzing pressure. Summer grzing hs vrible effects on fll diet protein. Summry In 1997 nd in 1998, four blocks of Sndhills rnge were used to exmine summer grzing time nd fll grzing pressure effects on fll diet qulity. Three pstures within ech block were grzed in June, July, or deferred from summer grzing ech yer. Multiple grzing pressures were creted by grzing cows t vrious stocking rtes in the fll. Diets were collected by esophgelly fistulted cows. In 1997, diet protein nd digestibility declined with incresing grzing pressure. In 1998, there were no effects of grzing pressure on fll diet protein or digestibility. July grzing reduced fll diet protein compred to June grzing in 1997, nd summer grzing reduced fll diet protein compred to no summer grzing in Introduction The effects of summer grzing dte nd fll-winter stocking rte in the Nebrsk Sndhills hve been evluted seprtely (1998 Nebrsk Beef Report, pp ). However, no dt hve been generted in the Nebrsk Sndhills to determine if the effects of fll-winter stocking rte on fll-winter diet qulity differ in pstures grzed t different times the previous summer (stocking rte by summer grzing dte interction). The mount of forge vilble for grzing per unit of lnd re vries cross yers, rnge sites nd mngement systems. Therefore, it often is more useful to mesure the mount of niml demnd for forge pplied per unit of forge vilble. Cumultive grzing pressure (CGP), mesured in niml unit dys (AUD) per metric ton of initil stnding forge (t), is wy to express niml demnd per unit of vilble forge. The effects of fll CGP on fll diet qulity hve not been evluted in the Nebrsk Sndhills. Defining the protein content nd digestibility of fll-winter diets cross vrious grzing systems will llow for the development of ccurte supplementtion protocols, lleviting inefficiencies ssocited with over-feeding or under-feeding supplements. The objective of this study ws to exmine summer grzing time nd fll (October-December) grzing pressure effects on Fll diet CP nd in vitro orgnic mtter digestibility (IVOMD). Experiment 1. Procedure Four blocks of rngelnd t the University of Nebrsk s Gudmundsen Sndhills Lbortory, Whitmn, Nebr., ech were seprted into three.74 cre pstures. The blocks were locted on snds rnge site in good to excellent condition nd dominted by little bluestem, pririe sndreed, snd bluestem nd switchgrss. Ech of the three pstures in ech block were rndomly ssigned to receive one of three summer grzing tretments in 1997: 1) no summer grzing, 2) grzing in lte- June by yerling cttle t.2 AUM/cre, nd 3) grzing in lte-july by yerling cttle t.2 AUM/cre. Beginning Oct. 9, 1997, six esophgelly fistulted cows (two cows/psture) were strtified by ge nd weight nd rndomly ssigned to pstures in the first block. Blocks were grzed sequentilly throughout the fll for seven dys ech, with the fourth period ending Nov. 22, Cows grzed ech.74 cre psture for the first four dys of ech 7-dy grzing period to crete cumultive stocking rte (SR) of.4 AUM/cre. On dy 5, the pstures were split in hlf by electric fence nd.37 cres of ech psture were grzed for two dys to crete cumultive SR of.8 AUM/cre. On dy 7, ech.37 cre pddock ws split in hlf nd cows grzed the remining.19 cres for one dy, for finl cumultive SR of 1.2 AUM/cre. Diets were collected by the two fistulted cows grzing ech psture when the cumultive Fll SR ws 0,.2,.4,.6,.8, nd 1.2 AUM/cre. Diets were immeditely frozen following collection. They were subsequently freeze dried, ground, nd nlyzed for DM, OM, CP, IVOMD nd undegrdble intke protein (UIP; 1998 Nebrsk Beef Report, pp ). Forge UIP ws clculted using the rte (Kd) of neutrl detergent insoluble CP (NDICP) between 2 nd 12 hours nd pssge rte (Kp) of 2.0% ((Kp/(Kd +Kp)) + undegrdble NDICP). To determine the mount of stnding forge per unit re, clipped smples were tken t rte of 10 per.19 cres with.25 meter squred rectngulr frmes prior to ppliction of fll grzing tretments. Smples were dried t 140 Fhrenheit for 48 hours prior to weighing. Cumultive grzing pressure ws clculted s the cumultive AUD pplied to given pddock (or subpddock) t the time of diet collection (Continued on next pge) Pge Nebrsk Beef Report

24 divided by the metric tons of forge initilly vilble (0 AUM/cre) in tht pddock. The effects of summer tretment, SR nd summer tretment SR were nlyzed in split-plot design. Whole plot error ws clculted s block summer tretment with SR s the sub-plot. Summer tretment effects were detected with contrsts (grzed versus deferred; June grzed versus July grzed). Simple regressions cross CGP were clculted for CP, IVOMD, nd UIP. Experiment 2. In 1998, summer grzing tretments were rndomly pplied to three.74 cre pstures in four blocks of uplnd rnge s described for Exp. 1. The blocks were locted on different site with less little bluestem thn the site used in the first experiment. Diets were collected by two esophgelly fistulted cows per psture on Oct. 17. Ech psture ws then split into one.37 cre nd two.19 cre pddocks. The three pddocks in ech psture were grzed simultneously by intct cows t either.4,.8, or 1.2 AUM/cre for three consecutive dys (two blocks t time) between Oct. 19 nd 24. Due to niml nd lbor constrints, diets were collected with esophgelly fistulted cows (two cows/pddock) seven weeks following the ppliction of fll grzing tretments. When post-grze diets were being collected, diets were tken in n djcent ungrzed psture to djust for ny effect of dvncing seson on diet qulity. Undegrdble intke protein ws not mesured in this experiment. Clipped smples were tken immeditely before ppliction of Fll grzing tretments. Other procedures nd nlyses were s described for Exp. 1. Results In Exp. 1, there were no SR summer tretment interctions for fll diet CP, IVOMD, or UIP (P >.50). The min effect of SR ws significnt for ll vribles (P <.01). Fll diet CP ws higher (P =.11) in pstures grzed in June (Tble 1) thn those grzed in July. Undegrdble intke protein (DM bsis) in the fll ws higher (P =.10) in Tble 1. Crude protein, undegrdble intke protein (UIP), nd in vitro orgnic mtter digestibility (IVOMD) of fll diets following vrious summer grzing dtes in the Nebrsk Sndhills (Exp. 1). Summer Tretment Item Deferred June July SEM CP, % OM b UIP, % DM c IVOMD, % Stndrd error of the men; n = 72. b Significnt contrst: June versus July (P =.11). c Significnt contrsts: Grzed versus Deferred (P =.10); June versus July (P =.14); clculted using rte of NDIN digestion (2 nd 12 hours) nd 2.0% rte of pssge. Tble 2.Crude protein nd in vitro orgnic mtter digestibility (IVOMD) of fll diets following vrious summer grzing dtes in the Nebrsk Sndhills (Exp. 2). Summer Tretment Item Deferred June July SEM CP, % OM b IVOMD, % Stndrd error of the men; n = 45. b Significnt contrst: Grzed versus Deferred (P =.09). summer grzed pstures thn deferred pstures, nd UIP tended to be higher (P =.14) in June versus July grzed pstures. Summer tretment hd no effect on IVOMD. Also in Exp 1., CP responded cubiclly (P <.01) to incresing CGP (Figure 1), declining from 8.6% pre-grzing (0 AUD/t) to 6.5% t 50 AUD/t. There were no effects of CGP on diet UIP content. Diet IVOMD lso responded cubiclly (P =.05) to incresing CGP (Figure 2), declining from 54% t 0 AUD/t to 50% t 50 AUD/t. In Exp. 2, no SR summer tretment interctions existed for CP or IVOMD (P >.15), nd SR ws not significnt for either vrible (P >.20). However, CP in fll diets from pstures deferred from summer grzing ws greter (P =.09) thn in diets grzed in the summer (Tble 2). There were no effects of CGP on CP or IVOMD. Downs (1998 Nebrsk Beef Report, pp ) found no response of summer grzing dte (deferred, June, or July) on the CP content of fll-winter diets in the Nebrsk Sndhills. In these two experiments, however, summer grzing dte did ffect CP in fll diets. Conditions such s precipittion, temperture, nd dte of first freeze my ffect how plnts respond to lte seson herbivory, thus ffecting diet protein content in the fll. The response of incresed UIP in June grzed pstures is similr to tht mesured by Downs (1997 Nebrsk M.S. Thesis). However, with vlues t 1.5% of DM, biologicl implictions to forging cttle do not likely exist. Indeed, degrdble intke protein (DIP), not UIP, hs been shown to be first limiting to cows grzing winter Nebrsk Sndhills rnge (1996 Nebrsk Beef Report, pp ). Crude protein (7.3 nd 8.5%) nd digestibility (52 nd 54%) vlues were lower in Exp. 1 thn in Exp. 2, respectively. Other dt hve indicted yer to yer vrition in fll-winter diet CP vlues. Dt from Gudmundsen Sndhills Lbortory showed not only different diet CP vlues collected in two consecutive yers, but CP content of diets chnged from December to Februry in the opposite direction ech yer (1993 Nebrsk Beef Report, pp. 8-10). The fll conditions during Exp. 2 (1998) included wrmer thn norml tempertures nd bove verge precipittion. Dt re not vilble s to the effects of environment on the response of diet qulity to incresing fll grzing pressure. Nevertheless, the CP nd IVOMD response ws different in Experiments 1 nd 2. Another explntion for the lck of response of CP nd IVOMD to fll CGP 2001 Nebrsk Beef Report Pge 24

25 CP (% OM) Figure 1. Chnge in CP of cow diets from uplnd Sndhills rnge collected cross multiple cumultive fll grzing pressures. Cubic response, P <.01. IVOMD, % Norml CGP Cumultive Grzing Pressure (AUD/t) Cumultive Grzing Pressure (AUD/t) Figure 2. Chnge in in vitro orgnic mtter digestibility (IVOMD) of cow diets from uplnd Sndhills rnge collected cross multiple cumultive fll grzing pressures. Cubic response, P <.05. in Exp. 2 could lie in the fct tht postgrze diets were collected seven weeks fter ppliction of fll tretments. Observtions indicted tht sedges regrew following the October grzing period; therefore the cows could hve collected some regrowth in December in ddition to residue remining fter the October grzing. As shown in Figures 1 nd 2, the decline in CP nd IVOMD cross CGP in Exp. 1 occurred with the first imposed grzing pressures. This is consistent with tht reported by Downs (1997 Nebrsk M.S. Thesis). It ppered tht when low stocking rtes (.2 AUM/cre), or imposed grzing pressures (5-10 AUD/ t) were reched, diet protein nd digestibility were reltively consistent irrespective of further increses in grzing pressure. After this initil decline, supplementl requirements of grzing cttle my remin constnt with incresing grzing pressures until the point when grzed forge intke is reduced by the mount of vilble forge. The rnge of norml grzing pressures in the Nebrsk Sndhills lso is shown in Figure 1. In 90-dy continuous grzing progrm with similr initil stnding forge s reported here, it would tke between 45 nd 90 dys of grzing before CP deficiency occurred in mture beef cow (180 dys pregnnt). Therefore, defining the decline in cow diet CP is importnt in determining both the timing nd mount of supplementtion required. The effect of yer on diet qulity my be lrger thn the effect of grzing pressure. Combining the two yers of diet qulity dt collected by Downs (1997 Nebrsk M. S. Thesis) nd the dt from the two experiments reported here, generliztions on winter supplement requirements to spring clving cows cn be mde. Across the four yers of dt, fll/winter diet CP rnged from 5% to 8.5% of OM (4.5 to 7.7% of DM). Likewise, fll/winter diet digestibility (TDN) rnged from 51% to 55%. With this rnge of diet CP, cow requirements for supplementl DIP re between 0 nd 230 grms/dy. If DIP requirements re met, supplementl UIP is not necessry until just prior to clving. Between 50 nd 120 grms/dy of supplementl UIP my be required in lst month of gesttion. With dequte forge vilbility, energy is not deficient to the mture cow until the lst six weeks before clving. If winter diets re 51% TDN, cows grzing rnge will be 1.6 Mcl/dy deficient in NEm t 45 dys pre-clving. The lck of n interction between fll stocking rte nd summer grzing dte ws consistent between experiments. Incresed fll grzing pressure cused reduction in CP nd IVOMD in one of two experiments. The decline in qulity occurred with the first levels of imposed grzing pressure. July grzed pstures hd lower CP vlues thn June pstures in Exp. 1, nd summer grzed pstures were lower in CP thn deferred pstures in Exp.2. 1 Trey Ptterson, reserch technicin; Terry Klopfenstein, Professor, Animl Science, Lincoln; Don Adms, Professor, Animl Science, West Centrl Reserch nd Extension Center, North Pltte; Wlter Schcht, Associte Professor, Agronomy, Lincoln; Ptrick Reece, Associte Professor, Agronomy, Pnhndle Reserch nd Extension Center, Scottsbluff; Jcki Musgrve, reserch technicin, West Centrl Reserch nd Extension Center, North Pltte; Amy Johnson, former grdute student. Pge Nebrsk Beef Report

26 Annul Forge Production nd Qulity Trils Burt Weichenthl Dvid Bltensperger Ken Vogel 1 Forge crude protein, digestibility nd vilble energy in smll grin nd sorghum forges will vry with vriety nd mturity t hrvest. Sorghum hybrids contining the brown midrib trit hve higher digestibility. Summry Two-yer forge trils showed higher dry mtter yields for winter triticle thn for winter whet while forge qulities were similr. Likewise, spring triticle cultivr hd higher dry mtter yields thn spring brley or ot cultivrs when hrvested for forge fter heding, nd forge qulities were similr. In summer trils, drylnd forge sorghum nd sorghum x sudngrss hybrids hd higher crude protein, digestibility nd energy vlues thn irrigted forges becuse they were not s mture. Lower lignin content nd higher digestibility resulted when the brown midrib trit ws present in forge sorghum or sorghum x sudngrss hybrids. Introduction Dt re limited on the forge production nd qulity potentil for currently vilble nnul forges. Chnges in production potentil nd feed qulity hve occurred, such s lower lignin content nd higher digestibility ssocited with the brown midrib (BMR) trit tht hs been crossed into some forge sorghum, sudngrss, sorghum x sudngrss nd corn hybrids. Forge trils were conducted over two yers to compre some of the newer forge cultivrs with some tht hve been round long enough to be considered stndrds. Forge production nd qulity were evluted for cerel forges grown under drylnd mngement nd for sorghum, sorghum x sudngrss, nd perl millet forges grown under drylnd or irrigted mngement systems. Procedure Drylnd winter whet nd triticle cultivrs were hrvested for forge t Med, McCook, nd Sidney in 1997 nd 1998 fter producing seed hed. Ten whet cultivrs were plnted, including Arphoe, Lmr, Longhorn, Pronghorn nd six experimentl cultivrs. Five triticle cultivrs were plnted, including Tricl, Newcle, nd three experimentl cultivrs. There were four replictions of ech cultivr t ech loction. Drylnd spring seeded cerel crops were hrvested s forge t Sidney in 1998 nd 1999 fter most of the cultivrs hd produced seed hed. There were two triticle, two brley, nd three ot cultivrs with four replictions of ech cultivr. All nnul forges were plnted in six row plots with double disc grin drill with 12 in between rows. All forge plots were hrvested with plot swther tht cut the center four rows. Mechnicl chopping of the forges llowed subsmpling for dry mtter nd forge qulity nlyses. Qulity results were vilble from 1998 trils only t the time this pper ws prepred. Summer drylnd forges were plnted t Sidney nd included one sudngrss, six sorghum x sudngrss, nd eight forge sorghum cultivrs. Forges were hrvested fter the mjority of cultivrs hd heded in growing sesons of 78 nd 75 dys in 1998 nd 1999, respectively. The plots were fertilized with 60 lb of N nd 40 lb of P 2 O 5 in 1998 nd 45 lb of N in Summer irrigted forges plnted t Scottsbluff included one sudngrss, five sorghum x sudngrss, nine forge sorghum, nd three perl millet cultivrs. The plots were hrvested fter the mjority of cultivrs hd produced seed hed in growing sesons of 82 nd 88 dys in 1998 nd 1999, respectively. They were fertilized with 120 of N nd 80 lb of P 2 O 5 s side dress in both yers. Forge qulity tests included percentges of dry mtter for totl nd nitrte nitrogen, neutrl detergent fiber, cid detergent fiber, cid detergent lignin nd in vitro dry mtter digestibility (IVDMD). The cid detergent fiber (ADF) vlues were used to clculte energy vlues s TDN, net energy nd metbolizble energy by using equtions listed by the Ntionl Forge Testing Assocition. Lest significnt differences t the 5% probbility level of incorrectly stting difference were determined for ech trit by using the generl liner model in the Sttisticl Anlysis Services computer progrm. Results Fll nd spring seeded cerel forge results re shown in Tble 1. Averges re shown for the 10 winter whet nd 5 triticle cultivrs hrvested t ech loction in 1997 nd Although differences in dry mtter forge yields were not lrge, the top yielding winter whet cultivr t ll three loctions ws Pronghorn, nd the top yielding winter triticle cultivr t McCook nd Sidney ws Newcle. Both of these cultivrs were developed by plnt breeders in the University of Nebrsk system. Forge crude protein (CP) nd ADF levels were similr mong the whet nd triticle culti Nebrsk Beef Report Pge 26

27 Tble 1. Production nd qulity of drylnd smll grin forges in University of Nebrsk trils in 1997, 1998, Winter Forges, b DMYLD CP NDF ADF IVDMD TDN NE m NE g ME Crop Loction lb/cre % % % % % Mcl/lb Mcl/lb Mcl/lb Whet Med Whet McCook Whet Sidney Whet Men Triticle Med Triticle McCook Triticle Sidney Men Spring Forges, c Crop Cultivr Triticle Brley Horsford Brley Westford Ot Monid Ot Russell Ot/Pe Russell/Pe Triticle Grce Ot Mgnum Men LSD Abbrevitions re: DMYLD = dry mtter yield, CP = crude protein, NDF = neutrl detergent fiber, ADF = cid detergent fiber, IVDMD = in vitro dry mtter digestibility, TDN = totl digestible nutrients, NE m = net energy for mintennce, NE g = net energy for gin, ME = metbolizble energy, LSD = lest significnt difference. b There were 10 whet nd 5 triticle cultivrs grown t ech loction ech yer in the winter forges. c Dry mtter yields re verges for two yers, but qulity is from 1998 only in the spring forges. Tble 2. Production nd qulity of drylnd summer forges t the University of Nebrsk High Plins Ag Lb, Sidney, NE, DMYLD c CP NO 3 N NDF ADF ADL IVDMD TDN NE m NE g ME Crop b Cultivr lb/cre % ppm % % % % % Mcl/lb Mcl/lb Mcl/lb SXS SX FS X FS Sweet N Red SXS Att-A-Grze FS XBMR SXS Sooner Sweet SXS SXS 94X SXS Nutri + BMR FS BMRX FS Cnex BMR FS X SXS Super Sweet ST FS Rox Ornge S Piper FS Erly Sumc Men LSD Abbrevitions re: CP = crude protein, NO 3 N = nitrte nitrogen, NDF = neutrl detergent fiber, ADF = cid detergent fiber, ADL = cid detergent lignin, IVDMD = in vitro dry mtter digestibility, TDN = totl digestible nutrients, NE m = net energy for mintennce, NE g = net energy for gin, ME = metbolizble energy, LSD = lest significnt difference. b Crop bbrevitions re s follows: SXS = sorghum x sudngrss, FS = forge sorghum, S = sudngrss. c Dry mtter yields re verges for two yers, but qulity is from 1998 only. vrs t ech loction, mking energy levels clculted from ADF similr lso. The top yielding spring cerel forge ws triticle cultivr The brley cultivrs rnked second nd third in dry mtter yields. Forge CP levels were similr with n verge of 8.7% of dry mtter. Energy levels were lso similr with n verge of 65% TDN, which ws the sme s in the winter forges. Dry mtter yields for drylnd summer forges in Tble 2 re n verge of trils in 1998 nd Dry mtter percentges, plnt heights nd mturity scores re not shown, but were similr between yers. Crude protein levels for 1998 rnged from 13 to 9.4% of dry mtter, which ws consistent with the mturity stges tht rnged from boot to heded. Producers who wnt summer forge high in crude protein nd digestibility should hrvest crops more thn once seson when the crops hve regrowth cpbility. Other producers my wnt more dry mtter yield with single cut system when the crude protein (Continued on next pge) Pge Nebrsk Beef Report

28 Tble 3. Production nd qulity of irrigted summer nnul forges t the UNL Pnhndle Res. & Ext. Center, Scottsbluff, NE, DMYLD c CP NO 3 N NDF ADF ADL IVDMD TDN NE m NE g ME Crop b Cultivr lb/cre % ppm % % % % % Mcl/lb Mcl/lb Mcl/lb SXS Super Sweet ST FS XBMR FS Sweet N Red SXS Att-A-Grze FS X SXS Sooner Sweet FS Cnex BM FS X SXS Nutri + BMR SXS SXS 94X FS Erly Sumc FS FS PM Meg Mil FS Rox Ornge S Piper PM P10XIM FS BMRX PM HPM Men LSD Abbrevitions re: DMYLD = dry mtter yield, CP = crude protein, NO 3 N = nitrte nitrogen, NDF = neutrl detergent fiber, ADF = cid detergent fiber, ADL = cid detergent lignin, IVDMD = in vitro dry mtter digestibility, TDN = totl digestible nutrients, NE m = net energy for mintennce, NE g = net energy for gin, ME = metbolizble energy, LSD = lest significnt difference. b Crop bbrevitions re s follows: SXS = sorghum x sudngrss, FS = forge sorghum, S = sudngrss, PM = perl millet. c Dry mtter yields re verges for two yers, but qulity is from 1998 only. nd TDN contents re dequte for the nimls tht will consume the forge. Dry mtter yields for irrigted summer forges re shown in Tble 3 s n verge of 1998 nd 1999 trils. In Tbles 2 nd 3, cultivrs with n X before or fter numbers or nme were experimentl cultivrs in the yers of these trils. High yielding cultivrs included both forge sorghum nd sorghum x sudngrss hybrids. Some brown midrib hybrids hd good yields but showed some lodging in the single hrvest system tht llowed them to grow 6 to 7 ft tll, but this ws lso true for some non- BMR hybrids. Forge qulity results shown for 1998 indicte vrition in CP nd IVDMD, which often is due to mturity differences when hrvested. However, the emergence of summer forges with incresed digestibility, such s the brown midrib cultivrs in forge sorghum, sorghum x sudngrss, perl millet nd corn hybrids, brings new opportunities for improved niml performnce through grzing or feeding of these forges. Reduced lignin fiber content of these forges llows for greter digestibility, but multiple hrvest or grzing systems my be needed to minimize lodging problems tht cn occur if they get too tll. In both the irrigted nd drylnd trils in 1998, the highest IVDMD vlues were ssocited with the lowest cid detergent lignin percentges which re typicl for mny BMR hybrids. Nitrte nitrogen levels in Tbles 2 nd 3 were generlly below the 2000 ppm level often listed for initil toxicity concern for ruminnts. However, previous reserch with similr forges in western Nebrsk showed some potentilly toxic nitrte levels in irrigted forge in the first of two hrvests during the summer, especilly with high nitrogen fertility in the soil. Thus, nitrogen ppliction rtes will need to be mnged crefully long with mturity stge t hrvest to chieve stisfctory levels of CP without incresing nitrtes to toxic levels. The choice of n nnul forge crop nd cultivr my depend more on the time forge is needed in the grzing or hrvested forge system rther thn on differences in yield potentil. Fitting forge crop into cropping system would be n importnt considertion. Also, equipment requirements for the shorter nnuls, like smll grin or foxtil millet forges, my lredy be in n opertion for other hy crops, wheres equipment needed to esily hrvest nd feed the tller forges my be unique. Getting the thicker stemmed forges to dry down in resonble time period for mking hy will usully require crimping ction of the forge during cutting. The emergence of hybrids with higher digestibility my enhnce grzing of stnding or windrowed summer nnul forges during the winter. 1 Burt Weichenthl, professor, Animl Science, Dvid Bltensperger, professor, Agronomy, Pnhndle Reserch nd Extension Center, Scottsbluff; Ken Vogel, professor, Agronomy nd reserch geneticist, USDA-ARS, Lincoln Nebrsk Beef Report Pge 28

29 Compenstory Growth nd Slughter Brekevens of Yerling Cttle D. J. Jordon Terry Klopfenstein Todd Milton Rob Cooper 1 Incresed winter gins resulted in hevier finl weights nd incresed profits ($/hed) when compred to nimls wintered on miniml input system or clf finishing. Summry A two-yer summry of growing/ finishing systems indictes tht steer clves wintered t 1.5 lb/dy hd lower slughter brekeven (P <.05) costs compred to nimls wintered t 0.5 lb/dy. Additionlly, feeding wet corn gluten feed s n energy source to increse winter gins tended (P <.15) to produce slughter brekevens which were lower thn the sme winter gins produced by feeding corn. Restricting niml gin over the winter ( lb/dy) resulted in 25-32% compenstion on grss compred to controls (1.5 lb/dy). Comprison of clf finishing vs. yerling growing/finishing systems showed tht steers wintered with fst rte of gin (1.5 lb/dy) profited $28.85/hed compred to losses by steers wintered with slow rte of gin (0.5 lb/dy; $-30.24/hed) or clf finishing ($-20.87/hed). Introduction Mny bckgrounding systems vry in length, grow cttle t vrious rtes of gin, nd re designed round vilble resources. Becuse producers nd resources vry widely, different degrees of compenstory growth re experienced bsed on wintering conditions. Predicting the mount of compenstory growth bsed on gin during the winter nd/or feed resources used will llow producers to mke informed nd economiclly sound decisions when evluting growing/finishing progrm. If lrge nd relible compenstion response cn be chieved, bckgrounding nimls with miniml inputs should result in incresed profitbility. However, reserch conducted t the University of Nebrsk indictes tht compenstion of nimls bckgrounded t 0.5 lb/dy is consistently round 30% compred to nimls wintered t 1.5 lb/dy (2000 Nebrsk Beef Cttle Report, pp ; 1999 Nebrsk Beef Cttle Report, pp ). Therefore, in the bsence of greter compenstion, nimls must be bckgrounded t incresed rtes of winter gin for mximum profits. The objectives of this report were 1) to exmine the compenstory growth response of yerling steers on grss following bckgrounding nd evlute subsequent slughter brekevens, nd 2) to compre profitbility of clf finishing nd growing/finishing systems. Yerling Trils Procedure Wintering Period. One hundred eighty medium-frmed english cross steers (519 lb) were used in ech of two yers. Steers were purchsed in the fll nd llowed 28-dy cclimtion period. Steers were wintered on cornstlks from bout Dec. 1 through Febr. 15 (phse I), nd plced in drylots from Febr. 16 through My 1 (phse II). Cttle were ssigned rndomly to one of five tretments used to estblish winter gins for subsequent evlution of compenstory growth on grss. Tretments were: 1) Fst -gining steers supplemented with wet corn gluten feed (WCGF) for the entire winter, 2) Fst -gining steers supplemented with corn (CORN) for the entire winter, 3) Intermedite -gining steers fed to gin fst (using wet corn gluten feed) during phse I followed by slow rte of gin in phse II (FAST/SLOW), 4) Intermedite -gining steers fed to gin slow during phse I followed by fst rte of gin (using wet corn gluten feed) in phse II (SLOW/FAST), nd 5) Steers fed to gin slow for the entire wintering period (SLOW; Figure 1). Cttle were mnged in three groups during the winter. In phse I, WCGF steers (group 1) were supplemented with 5 lb/hed/dy (DM bsis) of wet corn gluten feed nd 0.18 lb/hed/dy (DM bsis) of minerl supplement, group 2 (CORN) consisted of steers which received 4 lb/hed/dy (DM bsis) of corn nd 1.8 lb/hed/dy (DM bsis) of sunflower mel-bsed supplement, nd group 3 (SLOW) consisted of steers which grzed cornstlks nd received 1.8 lb/hed/dy (DM bsis) of the sme sunflower mel bsed supplement. In phse II, hlf of the WCGF steers were switched to the SLOW tretment nd hlf of the SLOW steers were switched to the WCGF tretment, resulting in FAST/SLOW nd SLOW/FAST tretments (Figure 1). During phse II, WCGF steers received mmonited whet strw d-libitum, 5 lb/hed/dy (DM bsis) wet corn gluten feed, nd 0.14 lb/ hed/dy (DM bsis) of minerl supplement. Steers on the CORN tretment received mmonited whet strw d-libitum, 4 lb/hed/dy (DM bsis) rolled corn, 0.6 lb/hed/dy (DM bsis) of the sunflower mel-bsed protein supplement, nd 0.2 lb/hed/dy (DM bsis) of minerl supplement. The SLOW steers received d-libitum mmonited whet strw nd 0.2 lb/ hed/dy (DM bsis) of minerl supplement. Summer Period. On bout My 1, steers were weighed, fly tgged, nd implnted with Synovex S. In yer 1, steers were plced on bromegrss ner Med, NE for 45 dys (April 29, 1998 through June 12, 1998). On June 13, 1998, steers were weighed nd shipped to ntive wrm-seson pstures ner Rose, NE where they remined until (Continued on next pge) Pge Nebrsk Beef Report

30 Sept. 2, 1998 (82 dys). On Sept. 3, 1998, steers were returned to Med, nd grzed bromegrss re-growth until Sept. 28, 1998 (26 dys). Steers were mnged in one group throughout the summer. Steers were rotted on bromegrss pstures in lte spring nd erly fll so tht forge never becme limiting to steer performnce. On wrm-seson pstures, steers were rotted between two 320 cre pstures (totl = 640 cres) in the sme mnner. In yer 2, it ws necessry to chnge the psture mngement strtegy following poor grss gins in yer 1. Becuse the Rose, NE loction contins significnt low-lnd res, poor gins were likely due to significnt cool-seson grsses. Steers were sent to tht loction in mid-june, nd cool-seson grsses hd likely mtured, contributing to decresed steer performnce. Therefore, in yer 2, cttle were mnged in two groups. One group ws sent to Rose, NE while the other group remined on cool-seson grss t Med, from My 4, 1999 through October 5, Agin, n effort ws mde to mnge both groups so tht forge qulity nd quntity never becme limiting to steer performnce. Finishing Period. In both yers, upon removl from grss, ll steers were implnted with Revlor-S nd plced into the feedlot for finishing (18 hed/ pen). Steers were dpted to the finishing diet in 21 dys using four step-up diets contining 45, 35, 25, nd 15% roughge fed for 3, 4, 7, nd 7 dys, respectively. The finl diet (7.0% roughge) ws formulted to contin minimum of 12% CP,.7% C,.35% P,.6% K, 30 g/ton monensin, nd 10 mg/kg tylosin (DM bsis). The finishing diet contined 40% wet corn gluten feed, 48% high-moisture corn, 7.0% lflf, nd 5% supplement (DM bsis). Finl weights were clculted using hot crcss weight nd common dressing percentge (63). Hot crcss weights were obtined t slughter, nd ft thickness over the 12th rib, qulity grdes, nd yield grdes were gthered following 24-hr chill. Initil nd finl weights in the winter, summer, nd finishing periods were the verge of two consecutive dy weights following three dys of limit feeding Phse I WCGF CORN SLOW Phse II Figure 1. Tretment structure. CORN WCGF SLOW WCGF SLOW common diet contining 50% wet corn gluten feed nd 50% lflf hy fed t 2% of body weight (DM bsis). Economic Anlysis. Portions of the costs ssocited with ech tretment were different through the growing phses. Differences between systems in input costs will be noted, otherwise it should be ssumed tht inputs were similr. For initil steer cost, verge weight of pen ws multiplied by the 7-yer verge October clf price ($82.57/cwt.) for lb feeders (USDA Agriculturl Mrketing Service). Simple interest ws chrged on the totl sum of initil niml cost for the entire ownership period. All interest chrges discussed herein were bsed on simple 9.8% rte. Twenty-five dollrs/hed ws chrged for helth, processing, nd implnting. Interest ws chrged ginst helth cost over the entire ownership period. All three winter groups were chrged stlk chrge of $0.12/hed/dy during phse I. Interest ws chrged for hlf of the stlk grzing period plus the reminder of ownership. Also, during phse I, nimls in the WCGF group were supplemented with wet corn gluten feed (5lb/hed/dy; DM bsis) t cost of $102.99/ton (DM bsis), which is equl to corn price of $2.48/bu (s-is), nd minerl supplement ($36.40/ton; DM bsis) t the rte of 0.18 lb/hed/dy (DM bsis). Interest ws chrged on wet corn gluten feed nd minerl supplement for hlf of the stlk period nd for the reminder of ownership. Steers in the CORN group received 4 lb/hed/dy (DM bsis) of dry-rolled corn ($2.48/ bu; s-is) in phse I nd 1.8 lb/hed/dy (DM bsis) of protein supplement ($216.60/ton; DM bsis). Interest ws chrged on the cost of both corn nd protein supplement for hlf of the stlk grzing period plus the reminder of ownership. Steers in the SLOW group received the sme protein supplement in phse I s the CORN group t the sme feeding rte nd cost. Interest ws hndled in similr wy s described bove. During phse II, ll three groups were fed mmonited whet strw d-libitum. Intke of the groups ws monitored for cost clcultions (12.3, 15.1, nd 15.3 lb/hed/dy [s-is] for WCGF, CORN nd SLOW, respectively). Ammonited whet strw ws priced t $40/ton (s-is) nd interest ws chrged on strw for hlf of phse II plus the reminder of ownership. In phse II, steers in the WCGF group were supplemented with minerl supplement ($40.40/ton; DM bsis) t the rte of lb/hed/dy (DM bsis) nd wet corn gluten feed in the sme mnner s in phse I. Therefore, costs nd feeding rte for wet corn gluten feed were the sme in phse II s in phse I. Steers in the CORN group received corn in the sme wy s in phse I (feeding rte nd cost were similr), the sme protein supplement s in phse I t the rte of 0.6 lb/hed/dy (DM bsis), nd minerl supplement t the rte of lb/hed/dy ($86.00/ ton; DM bsis). Steers in the SLOW group were fed the sme minerl supplement s the CORN group t the rte of lb/hed/dy (DM bsis). Interest ws chrged on ll feed ingredients for ll groups for hlf of phse II plus the reminder of ownership. Stlk nd drylot yrdge ws chrged t the sme rte ($0.12, 0.11, nd 0.10/hed/dy for WCGF, CORN nd SLOW, respectively). Yrdge chrge differences were the result of incresed feeding costs ssocited with wet corn gluten feed nd corn compred to the SLOW group. The WCGF group ws chrged slightly more thn the CORN group becuse feed 2001 Nebrsk Beef Report Pge 30

31 truck ws required for wet corn gluten feed delivery s opposed to corn feeding which ws fed using pick-up truck. In ddition to the drylot yrdge chrge, dy chrge of $0.12/hed ws pplied to nimls in ll groups. Interest ws chrged on yrdge nd drylot costs for hlf of the respective period plus the reminder of ownership. For summer costs, grzing ws chrged t the rte of $0.50/hed/dy, nd interest ws chrged for hlf of the grzing period plus the reminder of ownership. Finishing costs include both feed nd yrdge. For feed, DM intkes for pen were determined nd diet cost of $114.20/ton (DM bsis) ws pplied. Feedlot yrdge ws pplied t $0.30/ hed/dy. Interest ws chrged on feed nd yrdge costs for hlf of the feeding period. Totl steer cost ws the sum of steer, winter, summer, nd finishing costs plus 2% deth loss. To clculte slughter brekeven, totl cost ws divided by finl weight. For ll supplementl ingredients, prices were determined bsed on ctul prices pid for those ingredients by the University of Nebrsk Feed Mill with 5% hndling fee. Supplementl ingredients include ll ingredients used in the winter protein nd minerl supplements, nd the supplementl ingredients used in the finishing diet. Wet corn gluten feed, whole corn, dry-rolled corn nd highmoisture corn were chrged on n equl dry bsis, nd price ws determined using 10-yer verge corn price for Nebrsk ($2.48/bu; s-is). A 10% shrink, processing, nd hndling fee ws pplied to corn nd wet corn gluten feed. Alflf in the finishing diet ws priced bsed on 10-yer verge price in Nebrsk ($60.72/ton; s-is) long with 10% mrkup. Clf vs. Yerling Comprison Experiments. The clf vs. yerling comprison used dt from four yers of clf finishing nd yerling growing/ finishing systems compiled t the University of Nebrsk from Clf finishing trils were chosen which hd begun in the fll of the yer, mening tht clves would hve been sorted from pool of nimls from which clves plced into the yerling systems originted. Yerling systems were hndled in the sme wy s described previously in the yerling trils; however, two dditionl yers of dt were used which were not reported previously. In ddition, only SLOW nd WCGF tretments were used in the comprison. Economic Anlysis. Economics for yerling systems were hndled in the sme mnner s described previously in the yerling trils. Clf finishing (CALF) slughter brekevens were clculted on pens of nimls from ech of the respective trils. Initil niml cost ws bsed on the USDA 7-yer verge October feeder cttle price discussed previously for the yerling trils ($82.57), indicting $78.44/cwt. for lb steer clves. However, dt from Oklhom suggests bout $2.66/cwt. (totl = $81.10/cwt.). should be dded bck to the purchse price for blck exotic cross steers (My 15, 2000 Feedstuffs, pp. 9). In our clf finishing trils, blck exotic cross steers were purchsed. Additionlly, clf purchse dt compiled t Nebrsk over the pst seven yers shows tht $81.65/cwt. ws pid for nimls weighing lb. Therefore, n verge between Oklhom nd Nebrsk dt ws used to rrive t purchse price of $81.38/cwt. for lb steers used for clf finishing. Interest ws pplied to initil cost of the niml over ownership. Helth, processing, nd implnting were ssessed flt rte of $25.00/hed. Feed chrges for the CALF tretment were bsed on the sme finishing diet cost chrged to the yerlings ($114.20/ton; DM bsis). Averge DM intke for ech pen ws used to determine feed consumption. Yrdge ws chrged t $0.30/hed/dy. Interest ws chrged on the finishing diet nd yrdge for hlf of the feeding period. A 2% deth loss ws pplied to ll of the clves. To clculte slughter brekeven, totl cost ws divided by finl weight. Profitbility ws determined for both CALF nd yerling (WCGF nd SLOW) tretments. Profitbility ws clculted using the seven-yer verge My-June USDA Choice slughter steer price ($66.21/cwt.; USDA Agriculturl Mrketing Service) for the CALF dt. Likewise, the seven-yer verge December-Jnury USDA Choice slughter steer price ($67.48/cwt.; USDA Agriculturl Mrketing Service) ws used for yerling dt. Yerling Trils Results Winter Period. Significnt ADG differences were estblished between fster gining tretments (WCGF nd CORN), intermedite tretments (FAST/ SLOW nd SLOW/FAST), nd the SLOW tretment (P <.05; Tble 1). More importntly, differences in finl winter weight (P <.05) were estblished for subsequent evlution of compenstory growth on grss (Tble 1). Summer Period. Animls on FAST/ SLOW, SLOW/FAST, nd SLOW tretments gined fster (P <.10) compred to nimls on fst gining tretments (WCGF nd CORN). No differences were noted in gins of steers on the two fster gining winter tretments (Tble 1). Gins of steers on the SLOW tretment nd intermedite tretments were similr (P >.10). Prior reserch conducted t the University of Nebrsk hs shown tht nimls restricted to be 50 lb lighter compred to fst gining group t the end of winter period (106 dys) fully compensted t the end of summer grzing (1989 Nebrsk Beef Cttle Report, pp ). In contrst, nother study demonstrted tht nimls more severely restricted (150 lb weight difference; 160 dys) only compensted 20% t the end of summer grzing (1998 Nebrsk Beef Cttle Report, pp ). In the present study, intermedite gining tretments begn the summer period pproximtely lb lighter thn nimls on WCGF nd CORN tretments. Following summer grzing, lb weight difference remined, resulting in compenstion of 33%. At the onset of summer grzing, steers on the SLOW tretment were pproximtely 145 lb lighter thn steers on fster gining tretments. By the end of the summer, the weight difference ws 108 lb, resulting in compenstion of 26%. Clerly, degree of restriction hd little (Continued on next pge) Pge Nebrsk Beef Report

32 effect on compenstion. In ddition, winter energy source (WCGF vs. CORN), length of restriction (intermedite tretments vs. SLOW), nd pttern of restriction (FAST/SLOW vs. SLOW/FAST) hd little or no effect on compenstion. Previous work which found tht full compenstion could be expected following summer grzing hs not been supported in four consecutive yers of compenstory gin work (two yers not reported here). Therefore, it ppers tht steers fed t fster rtes of winter gin cn be expected to mintin 70-80% of their weight dvntge following summer grzing. While summer gins reported here re below those typiclly seen in Nebrsk, other studies in which steers hve gined 2 lb/dy hve shown similr compenstion, indicting tht level of summer gin my not be key fctor (2001 Nebrsk Beef Cttle Report, pp ; 2000 Nebrsk Beef Cttle Report, pp ). Finishing Period. No differences mong winter tretments were noted in ADG, DM intke, or feed conversion (P >.10; Tble 1). Only differences in finl weight were pprent which re crryover from differences imposed in the winter. Economic Anlysis. Steers on the WCGF tretment tended (P <.15) to hve lower brekeven compred to steers on the CORN, FAST/SLOW, nd SLOW/FAST tretments (Tble 2). Animls on the SLOW tretment hd the highest brekeven (P <.05). Finl weight ppers to be the lrgest single fctor which ccounts for reduced slughter brekeven (P <.0001; s finl weight increses, slughter brekeven decreses), ccounting for 78% of the vrition. Becuse of incresed winter weight gin nd little summer compenstion by steers in the intermedite nd SLOW tretments, steers on the WCGF tretment hd lower slughter brekeven. Brekeven differences between WCGF nd CORN tretments re due to incresed winter inputs (protein supplement) for the CORN tretment, wheres wet corn gluten feed supplied energy, protein, nd minerls in one pckge. Tble 1. Steer performnce nd crcss dt. Item WCGF CORN FAST/SLOW SLOW/FAST SLOW Winter Dys Initil weight, lb ADG, lb 1.48 b 1.43 b 0.89 c 0.96 c 0.49 d Finl weight, lb 747 b 739 b 658 c 661 c 598 d Summer Dys ADG, lb 1.29 e 1.26 e 1.46 f 1.45 f 1.52 f Finl weight, lb 944 b 932 b 881 c 883 c 830 d Finishing Dys ADG, lb DMI, lb/dy Feed/gin g Finl weight, lb h 1396 b 1389 b 1337 c 1338 c 1276 c Crcss Dt Crcss weight, lb 879 b 875 b 842 c 843 c 804 d Yield grde Ft thickness, in.48 b.46 bc.46 bc.43 d.44 cd Qulity grde i 522 bc 527 c 513 bcd 502 cd 500 d WCGF = wet corn gluten feed; CORN = corn; FAST/SLOW = fst gin then slow winter gin; SLOW/FAST = slow gin then fst winter gin; SLOW = slow winter gin. bcd Mens within row with unlike superscripts differ (P <.05). ef Mens within row with unlike superscripts differ (P <.10). g Feed/gin ws nlyzed s gin/feed. Gin/feed is the reciprocl of feed/gin. h Clculted from hot crcss weight djusted to common dressing percentge (63). i Qulity grde: = Select, = Choice. Tble 2. Economics nd slughter brekevens. Item WCGF CORN FAST/SLOW SLOW/FAST SLOW Steer cost, $ Helth Winter costs, $ Feed Yrdge Summer costs, $ Grzing Finishing costs, $ Yrdge Feed Totl costs, $ Finl weight, lb 1396 b 1389 b 1337 c 1338 c 1276 d Brekeven, $/100 lb e b b b b c WCGF = wet corn gluten feed; CORN = corn; FAST/SLOW = fst gin then slow winter gin; SLOW/FAST = slow gin then fst winter gin; SLOW = slow winter gin. bcd Mens within row with unlike superscripts differ (P <.05). e Slughter brekeven price. Tble 3. CALF vs. yerling steer performnce. Item CALF FAST SLOW Winter initil wt., lb Winter ADG, lb Grss initil wt., lb Grss ADG, lb Dys on feed Feedlot initil wt., lb Feedlot ADG, lb b 4.26 c DM intke, lb/dy b 28.9 c Finl wt., lb d b 1242 c Crcss wt., lb b 783 c Ft, in Yield grde bc Mens within row with unlike superscripts differ (P <.05). d Clculted from hot crcss weight djusted to common dressing percentge (63) Nebrsk Beef Report Pge 32

33 Gin/Feed b b b b P <.05 P <.05 4 P < Yer Figure 2. Feed efficiency yer tretment interction. $/cwt. $/hed b b b b P <.05 4 P <.05 P <.05 4 P < Yer Figure 3. Slughter brekeven yer tretment interction. b b c P <.05 P <.05 P <.05 P < b -60 c Yer Figure 4. Profit/loss yer tretment interction. c b b b 12 b CALF WCGF SLOW CALF WCGF SLOW CALF WCGF SLOW Clf vs. Yerling Comprison Animls on the CALF tretment gined slower nd consumed less feed compred to yerling systems (P <.05; Tble 3). For feed efficiency, yer tretment interction ws evident (P <.05; Figure 2). In 1995 nd 1996, clves were more efficient compred to the yerling systems (P <.05); however, in 1997 no differences in efficiency were noted (P >.05). Likely, the reson for the discrepncy in 1997 is tht clves on feed in the spring of 1998 encountered significnt mud which reduced performnce (ADG nd feed efficiency). In 1998, clves were more efficient (P <.05) thn both yerling tretments, nd the WCGF tretment ws more efficient (P <.05) compred to SLOW. The WCGF tretment produced crcsses which were hevier (~75 lb; P <.05) compred to SLOW nd CALF tretments. In terms of slughter brekeven, yer tretment interction (P <.05; Figure 3) ws evident. In 1995, WCGF nd CALF tretments resulted in similr brekevens, while SLOW tretment brekevens were higher (P <.05). In 1996, the WCGF tretment hd the lowest (P <.05) brekeven compred to CALF which ws lower (P <.05) compred to SLOW. In 1997 nd 1998, the WCGF tretment hd lower brekeven (P <.05) compred to both CALF nd SLOW. When compring groups which were fed (nd therefore sold nd slughtered) t different times, slughter brekeven my not be pproprite. Profitbility is better mesure becuse it ccounts for different mrketing times. Figure 4 shows the profitbility of ech of the tretments within ech yer. Clf finishing filed to show profit in ll four yers, wheres the WCGF yerling system ws profitble in three yers. The SLOW yerling system ws profitble in 1998; however, it lso produced the lrgest losses in two of the yers exmined with the most substntil losses occurring in While not sttisticlly pproprite bsed on the yer tretment interction, verging profit/loss numbers cross yers is relistic in terms of producer profitbility. The WCGF yerling system ws (Continued on next pge) Pge Nebrsk Beef Report

34 dvntgeous compred to CALF or SLOW, showing n verge profit of $28.85/hed over the four-yer period. Losses incurred by CALF nd SLOW were $ nd /hed, respectively. Finl weight ws the lrgest determining fctor in terms of both slughter brekeven nd profit/loss, explining 47 nd 49% of the vrition, respectively. Steer purchse price cn hve reltively lrge impct on profitbility. Dt from Knss indictes tht lrge devitions in the price spred cn occur with chnges in the price of corn (2000 Knss Stte Cttlemn s Dy Report, pp ). For exmple, the price differentil between 500 nd 800 lb steers with below verge corn price ($1.68/ bu) is pproximtely $20.00/cwt.; however, when corn price rises to $3.52/bu, the price differentil cn diminish to $7.00/cwt. for the sme steers. Producers should be wre of the price differentil pid for clves for clf finishing compred to clves which will be grown in yerling progrm, s well s mrketing times nd expected prices received before mking decisions to bckground or plce clves on feed. In the present nlysis, the WCGF wintering system ws superior to either clf finishing or growing/finishing system utilizing slow rte of winter gin; however, severl fctors cn interct with slughter brekevens nd profitbility such s corn price, purchse price nd slughter cttle price. 1 D. J. Jordon, reserch technicin; Terry Klopfenstein, professor; Todd Milton, ssistnt professor; Rob Cooper, reserch technicin, Animl Science, Lincoln. Undegrdble Intke Protein Supplementtion of Compensting, Grzing Steers Kelly Creighton Mrk Ullerich Terry Klopfenstein 1 Yerlings wintered t fster rte of winter gin responded better to undegrdble intke protein supplementtion during the summer, however incresed gins were not mintined during the finishing phse. Summry A tril ws conducted to evlute the effect of previous winter gin on response to undegrdble intke protein (UIP) supplementtion during the summer grzing period. Steers wintered t the FAST rte of gin hd greter response to UIP supplementtion thn steers with SLOW rte of gin. Mximum response for FAST cttle occurred t 150 g/d of supplementl UIP, while SLOW cttle showed no response through 150 g/d. Forge DM intke ws similr for FAST nd SLOW cttle, therefore SLOW cttle consumed more s percentge of body weight. Incresed gins from UIP supplementtion were not mintined during the finishing phse. Introduction Becuse of the high degrdbility of protein in ctively growing forges, undegrdble intke protein (UIP) my be first limiting before energy (1991 Nebrsk Beef Report, pp ). Therefore, supplementtion of UIP should increse gins during the summer grzing phse. Compenstory gin typiclly occurs in nimls tht hve been previously restricted or mintined on low plne of nutrition, nd enhnced intke is often cited s mechnism for which compenstory gin occurs. Previous reserch t the University of Nebrsk hs shown tht the rte of winter gin nd subsequent compenstory gin ffects the response of grzing steers to UIP supplementtion but not dry mtter intke (DMI) during the summer phse (2000 Nebrsk Beef Report, pp ). Steers with higher dily gins during the winter phse respond more to UIP supplementtion, even though cttle with slower rtes of winter gin experience compenstory growth during the summer. Therefore, it ppers tht cttle with different degrees of compenstory gin hve different requirements for UIP. Additionlly, cttle wintered t different rtes of dily gin still consume the sme mount of DM. Therefore, the objectives of our study were to evlute the effects of previous winter gin on response to UIP supplementtion nd forge DMI during the summer grzing period. Procedure Forty-nine steers (503 lb; 11/24/98) were used in 2x7 fctoril tretment design. Steers were llotted rndomly to one of two rtes of winter gin, 1.5 (FAST, n=25) nd.5 lb/dy (SLOW, n=24). Steers then were rndomly ssigned to one of six UIP supplements (n=3) or n energy control (n=7). Protein supplements were formulted to deliver 75, 112.5, 150, 187.5, 225, or g/dy of supplementl UIP. The 2001 Nebrsk Beef Report Pge 34

35 ADG (lb) ADG (lb) UIP supplementtion (g/dy) Figure 2. Averge dily gin (lb) of steers during the finishing phse excluding UIP supp. levels >150 g/dy. Summer x winter interction (P<.10). Fst Slow Fst Slow UIP supplementtion (g/dy) Figure 1. Averge dily gin (lb) of steers during the summer grzing period excluding UIP supp. levels >150 g/dy. Summer x winter interction (P<.10). protein supplement ws composed of 74% Soypss (treted soyben mel), 19% fether mel, 3% molsses, nd 4% slt. The energy supplement consisted of 56% soyhulls, 9% tllow, 6% Crolc ( rumen protected ft), 24% molsses, nd 5% slt. Combintions of the protein nd energy supplements provided the grded levels of UIP nd ll supplements were formulted to be isocloric. Steers were individully fed supplements four dys per week. Steers grzed four 8-cre fertilized brome pstures in rottionl grzing system from My 5 to June 11. Steers were then moved to pstures contining mixture of wrm seson grsses nd were mintined there in four-psture rottionl system until the end of the tril Aug. 19. A fifth psture ws used in lte July becuse of slow regrowth of the wrm seson grsses due to drier thn norml conditions. Biweekly diet smples were collected vi ruminlly fistulted nimls nd smples were nlyzed for CP, UIP, nd IVDMD. An intke determintion period, consisting of two one-week periods, ws conducted while cttle grzed brome (erly June) nd wrm seson (mid-july) pstures. All steers receiving the energy control supplement (n=7) nd the highest levels of UIP (n=7) within ech winter tretment received Cptec continuous relese chromium bolus to estimte fecl output. Fecl grb smples were tken for five consecutive dys during ech week of ech intke period. Smples were composited within week for nlysis nd determintion of fecl output. Totl chromium pyout from the bolus ws verified using totl fecl collection with six bg steers. Forge intke ws clculted by dividing fecl output by forge indigestibility. At the end of the summer grzing phse, steers were ssigned within winter tretment to feedlot pens for finishing. Steers were stepped-up to the finishing rtion which consisted of 47% high moisture corn, 44% wet corn gluten feed, 5% lflf nd 4% supplement. All steers were fed for 106 dys, t which point nimls were slughtered nd crcss chrcteristics were recorded. Results A significnt winter gin by UIP supplementtion interction (P=.09) ws observed for summer grzing ADG; therefore, effects within winter tretment re reported (Figures 1 nd 2). A significnt qudrtic effect (P=.09) on ADG cross ll UIP levels ws detected for FAST cttle, with the mximum response occurring t the 150 g/dy level. SLOW cttle responded linerly (P=.02) to incresing UIP levels; however, the response ws negtive. Supplementl levels bove 150 g/dy cused reduction in gins of FAST cttle. Therefore, in order to determine response to UIP supplementtion within the rnge of positive effects, the dt were renlyzed excluding UIP levels greter thn 150 g/dy. These new nlyses showed FAST cttle responded linerly (P=.08;.44 lb/dy) to incresing UIP, while the SLOW cttle hd no response to UIP. Additionlly, SLOW cttle experienced compenstory growth nd hd higher gins overll (2.0 v. 2.7 lb/dy for FAST vs. SLOW cttle receiving the energy control, respectively). Therefore, cttle with slower ADG during the winter phse were ble to prtilly compenste for weight differences tht were creted by the winter tretment. Becuse of the length nd severity of restriction in the SLOW cttle during the winter, they were only ble to compenste 25% of the difference creted by the winter tretments (177 v. 143 lb for initil nd finl grzing weight differences, respectively). Crude protein, UIP (%DM), nd IVDMD verged 16.8%, 1.09%, nd 70.3%, respectively, for the brome pstures nd 15.5%, 1.40%, nd 60.6%, respectively, for the wrm seson pstures. Dietry UIP content ws mesured using n in situ neutrl detergent insoluble nitrogen (NDIN) technique, nd clculted using rte of pssge nd rte of digestion. (Continued on next pge) Pge Nebrsk Beef Report

36 Results from intke determintion re summrized in Tble 1. There ws significnt effect (P<.005) of forge type on forge intke. Therefore, mens within forge type re reported. Winter tretments did not ffect pounds of DMI during the brome or wrm seson grzing period. However, there ws winter tretment effect (P<.0001) when DMI ws expressed s percentge of body weight. For both forge types, FAST nd SLOW cttle consumed similr mounts of DM; however, due to weight differences creted by the winter tretments, the SLOW cttle consumed more DM s percentge of BW. The increse in consumption, when expressed s percentge of BW, hs been previously reported nd my prtilly explin the compenstory gin tht occurred with the SLOW cttle. A summer by winter tretment interction (P=.09) occurred for feedlot performnce. Therefore, dt were nlyzed within winter tretment. Additionlly, performnce dt were nlyzed excluding the sme tretment groups s described for ADG in the grzing phse (UIP levels >150 g/dy). Anlysis with these levels showed tht there ws no effect of summer supplementtion level on feedlot performnce in the SLOW cttle. A negtive liner effect (P=.09) of UIP supplementtion during summer grzing occurred on feedlot ADG in FAST cttle. Cttle tht responded to UIP supplementtion during the summer hd significntly lower ADG thn those cttle tht received the energy control nd lower levels of UIP during the grzing period. This decrese in gins llowed for cttle to compenste for weight differences creted by summer tretments. There were no differences (P>.3) in crcss chrcteristics due to summer tretments in either FAST or SLOW cttle. There ws n effect (P=.0002) of winter tretment on hot crcss weight since SLOW cttle were ble to only compenste 25% of the weight difference creted by winter tretments during the grzing phse. There were no other effects of winter tretment on crcss chrcteristics. Tble 1. Forge intke of steers within forge type. Winter tretment FAST SLOW SEM P-vlue Brome DMI, lb/dy DMI, % BW Wrm Seson DMI, lb/dy DMI, % BW Tble 2. Metbolizble protein blnces for steers during the summer grzing period. FAST SLOW Energy Protein Energy Protein Brome Actul gin, lb/dy ME llowble gin MP blnce, g/dy Wrm seson Actul gin, lb/dy ME llowble gin MP blnce, g/dy Performnce, intke nd diet composition dt were used to evlute the 1996 NRC computer model t the end of the tril. Actul DMI nd forge digestibilities were used for ech forge type, s well s ADG during ech grzing phse. Adjustments for NEm nd NEg were clculted using metbolizble energy intke (NE djuster = ( ) x MEI + ( )). Using the NE djusters, the metbolizble energy llowble ADG for the highest responding protein level ws clculted using the model. The metbolizble protein (MP) blnce ws then determined for the energy control nd highest responding protein level tretments. The model predicted tht the SLOW gining cttle were deficient in MP during the brome grzing period; therefore, the SLOW cttle should hve responded to UIP supplementtion (Tble 2). Additionlly, the model predicted the FAST cttle were deficient in MP while grzing brome, but tht this deficiency ws overly compensted for with UIP supplementtion. The model lso predicted neither group to be deficient during the wrm seson period. The NRC model inccurtely estimted MP blnce for cttle t different physiologicl sttes nd djustments need to be mde to the model to ccount for differences in efficiency creted by compenstory gin. Previous winter tretment nd subsequent compenstory gin do ffect the response to UIP during the summer grzing period. Cttle mintined t slower rte of gin during the winter nd experience greter degree of compenstory gin during the summer respond less to UIP thn those yerlings tht were wintered t FAST rte of gin. Additionlly, forge intke (in pounds) ws not ffected by winter tretment, however, slower cttle et more s percentge of body weight due to weight differences creted by the winter tretment. Body weight dvntges gined by supplementtion during the summer re completely compensted for during the finishing phse. We concluded tht supplementtion during the summer grzing period ws not economicl. 1 Kelly Creighton, grdute student; Mrk Ullerich, grdute student; Terry Klopfenstein, professor, Animl Science, Lincoln Nebrsk Beef Report Pge 36

37 Undegrdble Intke Protein Content of Corn Steep Compred to Soyben Mel Trey Ptterson Terry Klopfenstein D. J. Jordon Csey Wilson Ryn Mss Rick Stock 1 Undegrdble intke protein content of corn steep is pproximtely 30% of crude protein. Summry Thirty clves were used in n 84-dy growth tril to evlute protein efficiency of corn steep compred to soyben mel. Clves were individully fed bse diet supplemented with either 1) ure, 2) soyben mel, or 3) corn steep. Soyben mel nd corn steep were fed t grded levels replcing ure. In vitro mmoni relese nlyses showed the protein in both corn steep nd soyben mel to be pproximtely 30% undegrdble in the rumen. Clves fed corn steep hd similr protein efficiency to clves fed soyben mel, supporting the in vitro dt. Introduction Corn steep, byproduct of wet corn milling, is combintion of corn steep liquor nd distillers solubles. Corn steep liquor is concentrted solubles from the steeping process, contining soluble protein, vitmins, minerls, nd lctic cid. Distillers solubles contin sugr nd yest cells remining fter the distilling process. Corn steep is dded to beef cttle diets to supply both protein nd energy. Corn steep is lso dded to corn brn to form wet corn gluten feed. Corn steep nd wet corn gluten feed hve been shown to improve performnce in dry-rolled corn finishing diets (1997 Nebrsk Beef Report, pp ). Degrdble intke protein (DIP), or nturl protein degrded in the rumen, hs been implicted in the improved performnce. Corn steep hs not been ssocited with hving significnt undegrdble intke protein (UIP), due to the solubility of protein in steep liquor. However, the distillers solubles contin heted yest cells. Het processing hs been demonstrted to reduce the solubility of protein. Feeding heted brewer s yest to clves hs produced lower rumen mmoni concentrtions thn feeding live brewer s yest, indicting protein in the heted yest ws degrded to lesser extent in the rumen. In vitro mmoni relese dt indicted protein in distillers solubles ws 80.6% undegrdble nd protein in steep liquor protein ws 13.2 % undegrdble. This would mke typicl corn steep product (36% CP, DM bsis) hve UIP vlue of 33% of CP. The UIP content of corn steep, s mesured in the lbortory, hs not been vlidted in cttle feeding experiment. The hypothesis is tht corn steep protein is degrded to similr extent s soyben mel protein (30% UIP). The objective of this experiment ws to compre the UIP vlue of corn steep to soyben mel in growing clf diets. Tble 1. Composition of supplements fed to growing clves (percentge of DM). Ure Ingredient Control SBM b Steep c Brn Soyben mel 55.7 Corn Steep 88.9 Ure Diclcium Phosphte Limestone Slt Ammonium sulfte 0.4 Trce Minerl Premix Vitmin Premix Selenium Premix Supplement included in diet t 20% of DM. b Soyben mel supplement replcing ure control t 25, 50, 75 nd 100% of supplement DM. c Corn steep supplement replcing ure control t 25, 50, 75 nd 100% of supplement DM. Procedure Thirty clves ( lb) were strtified by sex nd rndomly llotted to tretment nd level within tretment. Three tretments were: 1) supplement to supply the degrdble intke protein requirement with ure nd corn brn (n = 6, ure control); 2) soyben mel replcing ure nd brn in the supplement t 25, 50, 75, or 100% of the supplementl CP (n = 3 per level, SBM); nd 3) corn steep replcing ure nd brn in the supplement t 25, 50, 75, or 100% of the supplementl CP (n = 3 per level, Steep). Diets were 40% sorghum silge, 20% corncobs, 20% dry corn brn, nd 20% supplement (DM bsis; Tble 1). Diets were formulted to contin minimum of 11.5% CP. All clves were fed to the sme percentge of body weight, with the feeding level strting t (Continued on next pge) Pge Nebrsk Beef Report

38 2.0% of body weight nd incresing to 2.6% over the course of the experiment. Diets were individully fed with Cln Gte system for 84 dys. Three dy weights were tken t the initition nd completion of the tril. Clves were implnted with Rlgro t the beginning of the experiment. Protein efficiency, clculted s gin bove the ure control over nturl protein intke bove the ure control, ws clculted for SBM nd Steep using the slope rtio technique. Non-liner regression ws used to determine the slope (protein efficiency) of the response lines before mximum gins were chieved. Slopes were compred with Modified T-Test for unequl vrinces. Results Clves on the ure control gined 1.6 lb/dy, nd the mximum gin relized by clves supplemented with either SBM or Steep ws 2.25 lb/dy. The regression of gin bove the ure control on nturl protein intke bove the ure control is shown in Figure 1. The mximum gin bove ure control,.57 lb, ws reched t.55 nd.62 lb of nturl protein intke bove the ure control for SBM nd Steep, respectively. The protein efficiency of Steep ( ) ws not different (P >.10) from SBM ( ). The bse diet supplied 5.6% nturl protein. Assuming the nturl degrdble protein requirement of rumen microbes ws met by the bse diet, ny response bove the ure control ws due to UIP supplied by the Steep nd SBM. Similr protein efficiency between Steep nd SBM indicte similr UIP contents. Nutrient concentrtions in the ure control diet nd the 100% SBM nd 100% Steep diets re shown in Tble 2. Both corn brn nd steep were higher in Gin Above Ure Control (lb/dy) SBM ( ) Nturl Protein Intke Above Ure Control (lb/dy) Figure 1. Protein efficiency of growing clves fed grded levels of soyben mel or corn steep (protein efficiency vlues in prentheses). Tble 2. Nutrient composition of diets fed to growing clves. Nutrient Ure Control 100% SBM 100 % Steep b DM, % CP, % of DM Clcium, % of DM Phosphorus, % of DM Sulfur, % of DM Soyben mel supplement replcing ure control t 25, 50, 75 nd 100% of supplement DM. b Corn steep supplement replcing ure control t 25, 50, 75 nd 100% of supplement DM. protein thn nticipted, so diets exceeded 11.5% CP. This does not chnge interprettion of results since 1) ll diets supplied dequte DIP, 2) protein efficiency clcultions tke into ccount both protein intke nd gin bove the control, nd 3) protein efficiency ws clculted prior to mximum gin. In vitro mmoni relese nlyses on steep smples from this tril showed tht corn steep protein ws 32.8% undegrdble, compred to 29.6% for soyben mel. These dt re consistent with previous mesurements in the lbortory. Steep ( ) While the stndrd errors re high for the protein efficiency vlues, the mens re quite similr. The conclusion of equl UIP vlues for Steep nd SBM is consistent with the in vitro mmoni relese dt. We conclude the UIP vlue of corn steep is pproximtely 30% of crude protein. 1 Trey Ptterson, reserch technicin; Terry Klopfenstein, professor, Animl Science, D. J. Jordon, Ryn Mss, nd Csey Wilson, reserch technicins, Lincoln; Rick Stock, Crgill Corn Milling, Blir, NE Nebrsk Beef Report Pge 38

39 Utiliztion of Bt Corn Hybrids in Growing Beef Steers Jeffrey Folmer Glen Erickson D.J. Jordon Todd Milton Terry Klopfenstein 1 The feeding vlue of corn residue or silge is similr between Bt nd nonbt corn hybrids. Summry Two trils were completed to evlute the efficcy of Bt corn hybrids for growing steers. After grin hrvest, tril 1 used two fields of N7333 Bt nd nonbt corn to evlute grzing performnce nd preference of growing steers. Tril 2 compred erly nd lte mturing vrieties (N4242 nd N7333, respectively) of Bt nd nonbt corn hybrids in corn silge-bsed growing diets. No differences in performnce or grzing preference were observed between N7333 Bt or nonbt residue. Steers fed corn silge from hybrids N4242 gined 11% fster (P>.01) nd were 7% more efficient (P>.01) thn those fed N7333 hybrids. Effects of the Bt trit in the corn silge growing study were inconsistent between hybrids. Introduction Bt corn hybrids hve been geneticlly engineered to control Europen corn borer without pesticide use. Corn residue nd corn silge re commonly used s feedstuffs for growing cttle. The objectives of this reserch were to 1) compre corn residue from Bt nd ner-isogenic nonbt corn hybrid on performnce nd grzing preference, nd 2) compre corn silge from two Bt corn hybrids nd their ner-isogenic counterprts on performnce of growing beef steers. Experiment 1 Mterils nd Methods Sixty-seven lrge frmed steer clves (625 lb) were used in two-prt 70-dy grzing tril. Thirty cres of lter mturing Novrtis N7333 Bt nd 28 cres of nonbt corn residue were divided into six pstures (3 Bt nd 3 nonbt) nd then stocked with 51 steers. To chieve equl stocking rtes (.69 AUM/cre), the three nonbt pstures were ech ssigned eight steers nd the three Bt pstures were ech ssigned nine steers. Prior to grzing, residul corn (bushels/cre) ws estimted by counting full nd prtil ers in ech of the six pstures. Steer weights were tken for two consecutive dys t the strt nd finish of the tril fter three-dy period of limit-feeding to equlize gut fill. The second component of experiment one evluted grzing preference for Bt nd nonbt corn residue. Sixteen steers grzed one psture contining equl cres of Bt nd nonbt corn residue for 70 dys. Animls were observed once dily between 6 nd 9.m., nd numbers of nimls grzing Bt nd nonbt residue were recorded. All steers (performnce nd preference experiments) received n equl mount of protein supplement (1 lb s fed/hd/d) to ensure protein did not limit performnce. Experiment 2 One hundred twenty-eight mediumfrmed steer clves (620 lb) were used in completely rndomized design with 2x2 fctoril rrngement of tretments. Erly vs lte mturing vrieties of Bt nd non-bt corn hybrids (N4242 nd N7333, respectively) were grown under similr gronomic conditions. Silges were hrvested t 3/4 milk line in the grin, nd stored seprtely in lrge plstic Agbgs. Silges were ensiled pproximtely 100 dys prior to initition of the experiment. Sixteen pens were used with eight steers per pen nd four replictions per tretment. Corn silge growing diets contined 90% corn silge nd 10% supplement (DM bsis, Tble 2). The supplements were formulted for dequte degrdble intke protein (DIP), undegrdble intke protein (UIP), vitmins, nd minerls bsed on the 1996 NRC Nutrient Requirements of Beef Cttle. All diets contined 20 g/t Rumensin. Steers were implnted with Rlgo Mgnum, nd fed for 101 dys. Weights were tken on two consecutive dys t the initition nd end of the experiment with interim weights tken pproximtely every 35 dys. Initil nd finl weights were obtined following three-dy period of equlized intke (2% of BW; DM bsis) to minimize differences in gut fill. Experiment 1 Results nd Discussion Grin yield for N7333 Bt ws 184 bu/cre nd ws 182 bu/c for the N7333 nonbt. These two corn fields were pproximtely 75% pivot irrigted nd 25% drylnd. Results of the grzing tril indicted no difference in steer performnce due to incorportion of the Bt trit (Tble 1). Previous Nebrsk reserch hs demonstrted high correltion (r=.79)between residul corn nd dily gin of steers grzing corn residue (Jordn et l., 1997). Low Europen corn borer pressure nd (Continued on next pge) Pge Nebrsk Beef Report

40 good hrvesting conditions contributed to the low mount of residul corn (1.0 nd 1.5 bu/cre, Bt nd nonbt respectively), which is typiclly 2-4% of the corn yield. These conditions lso contributed to lower thn expected dily gins. Previous reserch nd experience t the University of Nebrsk would predict the verge dily gin to be.9 to 1.2 lbs/dy. There ws no preference (F-test; P=.51) in grzing distribution between Bt nd nonbt vrieties. During the grzing period, 47.5% of the steers were observed grzing Bt residue, nd 52.5% of the steers were observed grzing nonbt residue (Tble 1). Experiment 2 Corn grin nd silge yield dt re summrized in Tble 3. These drylnd fields showed greter difference in grin yield between the Bt nd nonbt vrieties. Corn borer infesttion dt re lso summrized in Tble 3. These mesurements were tken from Aug. 28 through Sept. 1, The nonbt corn fields did incur some degree of Europen corn borer infesttion. Results from six strip trils in vrious loctions cross the stte showed n verge of n 11% infesttion rte (B. Siegfried, University of Nebrsk Entomology Deprtment, personl communiction). Results for the silge growing study re summrized in Tble 4. Dry mtter intke ws higher (P=.02) for steers fed the Bt hybrids compred with nonbt hybrids. Additionlly, N4242 tended (P=.09) to hve higher dry mtter intke compred to N7333. An interction (P<.05) ws observed for dily gin nd feed efficiency between corn hybrid nd incorportion of the Bt trit. Dily gin ws incresed 7% (P <.05) when N4242 Bt ws fed compred to its ner-isogenic nonbt counterprt. In contrst, incorportion of the Bt trit into N7333 depressed dily gin by 4% (P =.09) when compred with its nerisogenic nonbt counterprt. Feed efficiency ws improved 4% (P =.11) in steers fed N4242 Bt, compred with N4242 nonbt. Steers fed N7333 nonbt were 8% (P <.05) more efficient thn those fed the N7333 Bt. Although the Tble 1. Performnce nd grzing preference of growing steers grzing Bt nd nonbt corn residue in Experiment 1. Item Bt nonbt SEM P-Vlue Performnce Initil wt, lb End wt, lb ADG lb/dy IVDMD, % Residul corn bu/cre Grzing Preference Distribution b, % In vitro dry mtter digestibility mesured using modified procedures of Tilley nd Terry (1963). b Percentge of steers observed grzing Bt or non Bt corn residue. Tble 2. Composition of corn silge diets fed to growing steers in Experiment 2. Ingredients (DM%) N4242 Bt nd nonbt N7333 Bt nd nonbt Corn Silge Supplement Supplement Composition (%) Soyben Mel Sorghum Dry Roll Ure Limestone Slt Tllow Diclcium Phosphte Vit. Min. Premix Nutrient Composition (DM%) N4242Bt N4242 nonbt N7333 Bt N7333nonBt DM CP NDF ADF C P Tble 3. Yield of corn grin nd silge used in Experiment 2. Item N4242 Bt N4242 nonbt N7333 Bt N7333 nonbt % Infested Grin Yield bu/cre Silge Yield t/cre DM t/cre b Indictes percentge of plnts infested with live lrve. b Silge yield multiplied by ctul silge dry mtter content. Tble 4. Performnce (101 dys) of growing steers in experiment 2 fed Bt nd nonbt silge. Gne* Item N4242 Bt N4242 N7333 Bt N7333 SEM Gene Hybrid Hyb. Initil wt, lb End wt, lb 944 b 923 bc 898 d 910 cd DMI lb/d ADG, lb 3.22 b 2.99 c 2.76 d 2.86 cd < Feed / Gin 5.98 b 6.22 bc 6.81 d 6.33 c <0.01 <0.01 Gene = min effect of Bt genetics; Hyb = min effect of hybrid ; Gne*Hyb = interction of Bt gene nd hybrid. bcd Mens in the sme row not bering common superscript differ (P<.05) Nebrsk Beef Report Pge 40

41 Tble 5. Chemicl nlysis of silges used in Experiment 2. Item (% of DM) N4242 Bt N4242 nonbt N7333 Bt N7333 nonbt SEM DM % Ash CP NDF ADF PL ADL b Strch h NDF Dig. c IVDMD d Permngnte lignin mesured ccording to Goering nd Vn Soest (1971). b Acid detergent lignin mesured ccording to Goering nd Vn Soest (1971). c 30-hour neutrl detergent digestibility mesured in vitro. d In vitro dry mtter digestibility mesured using modified procedures of Tilley nd Terry (1963). interction ws observed for dily gin nd efficiency, steers fed the N4242 gined 11% fster (P<.01) nd were 7% more efficient (P<.01) thn those fed corn silge produced from N7333. The dt from these experiments suggest incorportion of the Bt trit hs no effect on corn residue vlue or preference in grzing beef steers. Producers cn tke dvntge of incresed yields nd reduced pesticide use with Bt corn hybrids without dverse effects on corn residue grzing performnce. Stocking rtes my need to be djusted for Bt hybrids becuse of the potentil reduction in residul corn, or more supplementl feed my be needed to mintin dily gin compred with nonbt hybrids. The interction of hybrid genetics nd incorportion of the Bt trit observed with corn silge growing diets is difficult to explin, nd my be relted to slight chnges in the chemicl composition of the silges (Tble 5). Most importntly, hybrid genetics hve lrger influence on dily gin nd feed efficiency of growing steers fed corn silge-bsed diets compred with chnges ssocited with incorportion the Bt trit in these hybrids. 1 Jeffrey Folmer, grdute student; Glen Erickson, D.J. Jordn, reserch technicins; Todd Milton, ssistnt professor; Terry Klopfenstein, professor, Animl Science, Lincoln. Wet Corn Gluten Feed Supplementtion of Clves Grzing Corn Residue D. J. Jordon Terry Klopfenstein Todd Milton 1 Feeding wet corn gluten feed to clves grzing cornstlks increses weight gin bove non-fed controls. The optimum feeding level is 6.0 lb DM/hed/dy which cn result in lb/dy gin. Summry Incrementl levels of wet corn gluten feed were fed to clves grzing corn residues. Bsed on sttisticl nd economicl nlysis of the dt collected, feeding wet corn gluten feed ( lb/ hed/dy; DM bsis) will increse stocking rte on corn residue nd reduce winter costs by 11%. Given tht 3.5 lb DM/dy wet corn gluten feed will meet the protein nd phosphorus needs of clves, nd feeding bove 6.0 lb/d will not increse gins, wet corn gluten feed should be fed t lb DM/dy, producing gins from lb/dy. Introduction Wet corn gluten feed hs roughly the sme energy vlue s corn (NEg = Mcl/lb), is moderte in protein (23% CP) nd phosphorus (0.95%), is pltble, nd is sfe to feed in terms of little or no risk of cidosis or founder. With the high concentrtion of nutrients discussed, WCGF supplies severl expensive nutrients in one pckge. Feeding five lb of WCGF (DM/hed/ dy) is sufficient to meet the metbolizble protein requirement of clves grzing corn residues. However, no niml performnce trils hve been conducted to specificlly determine the optimum feeding level of WCGF to clves grzing corn residues. The objective of our study ws to evlute clf growth response to incrementl levels of wet corn gluten feed supplemented on corn residues in the lte fll nd erly winter. Procedure A steer growth tril ws conducted from Oct. 27, 1999 through Jn. 13, 2000 using thirty-seven crossbred steer clves (552 lb) which were individully fed supplement while grzing corn residues. Steers were ssigned rndomly to one of seven levels of supplement (2.0, 2.75, 3.5, 4.25, 5.0, 5.75, nd 6.5 lb of DM/hed/dy). The control tretment (7 hed) consisted of sunflower mel- (Continued on next pge) Pge Nebrsk Beef Report

42 bsed supplement fed t 2 lb/hed/dy (DM bsis) tht ws formulted to meet the degrdble intke protein (DIP) requirement of the steers. The second tretment (5 hed) ws combintion of WCGF (68%) nd sunflower mel (32%) fed t 2.75 lb DM/hed/dy. Sunflower mel ws required in the second tretment to meet DIP requirement of the steers. The remining 5 tretments (5 hed/tretment) consisted entirely of WCGF (3.5, 4.25, 5.0, 5.75, nd 6.5 lb/hed/dy; DM bsis). All steers were individully fed the pproprite mount of supplement once dily using Cln electronic gtes. Ech morning t pproximtely 6:30, steers were gthered for feeding. Steers were llowed mximum of one hour to consume the respective supplement offered. Following feeding, steers were returned to the cornstlk field. Four 7.4 cre fields were llocted for grzing. Steers were llowed ccess to new pddock when visul pprisl indicted tht lef nd husk mteril ws limiting. Initil nd finl weights were the verge of three consecutive-dy weights following three dys of limit feeding common diet contining 50% wet corn gluten feed nd 50% lflf hy fed t 2% of body weight (DM bsis). Results Steers on the control tretment gined 0.91 lb/dy. Averge dily gin incresed up to 1.86 lb/dy s WCGF ws included t the 6.5 lb DM/hed/dy level. When non-liner sttisticl nlysis ws pplied to the dt, it predicted tht gins leveled off t 6.0 lb DM (Figure 1). The nlysis suggests feeding WCGF bove 6.0 lb DM/dy would not increse gins nd presumbly, the cttle would begin to replce stlk intke with WCGF. Over the pst four yers, reserch conducted t the University of Nebrsk hs used 5.0 lb/hed/dy (DM bsis) of WCGF to increse winter gins (2001 Nebrsk Beef Cttle Report, pp ). Bsed on the previous reserch, feeding WCGF in the winter will reduce slughter brekeven compred to feeding protein supplement similr to the control Gin, lb/dy Slope = Stndrd Error = Mx. Gin = 1.88 lb/dy Stndrd Error = Level WCGF Figure 1. Dily gin of steers supplemented with wet corn gluten feed on cornstlks. Tble 1. Supplement effects on cornstlk intke predicted by two methods. Supplement Intke NRC Computer Model Stlk Intke Eqution b Vlues expressed s DM lb/hed/dy. b Eqution: RI = (0.0365W SD(SI))/1-RD, where RI = Residue Intke, SD = Supplement Digestibility, SI = Supplement Intke, nd RD = Residue Digestibility. tretment in the present study. The reduction in slughter brekeven hs been ttributed to incresed winter weight gin which is mintined throughout summer grzing nd finishing, resulting in more sle weight. Therefore, feeding 6.0 lb DM/hed/dy of WCGF might increse winter weight gin nd should further reduce slughter brekevens compred to feeding 5.0 lb DM/hed/dy. Feeding WCGF to clves grzing corn residues should increse the crrying cpcity of the cornstlks. Estimtes of cornstlk intke were determined from two sources: the 1996 Nutrient Requirements of Beef Cttle computer model nd n eqution developed specificlly to predict corn residue intke from residue digestibility nd fecl output (1989 Journl of Animl Science, pp ). Tble 1 shows the intke predictions bsed on ech model. In order to predict stlk intke from the 1996 NRC computer model, net energy djustments were mde bsed on nother rticle contined within this report (2001 Nebrsk Beef Cttle Report, pp ). Cornstlk intke ws first predicted bsed on the stlk prediction eqution for ech level of supplementtion. Once stlk intke ws estblished, it ws used to determine the TDN concentrtion of the totl diet nd net energy djustment ws clculted nd pplied to the 1996 NRC computer model. The 1996 NRC computer model then ws used to predict stlk intke to determine how comprble the vlues were between the two sources. Tble 1 shows the stlk intke predicted by the 1996 NRC computer model. While the predicted intkes do not lwys gree, especilly t higher supplement intkes, true vlues should fll within the rnge of the two intke predictions t given level of supplementtion. Therefore, higher levels of WCGF ( lb/hed/dy DM) reduced cornstlk intke by 10%, from bout 10.1 lb/hed/dy (DM bsis) with low level supplementtion to 9.1 lb/hed/ dy (DM bsis). Economic nlysis of winter supplementtion of WCGF ( Nebrsk Beef Report Pge 42

43 Nebrsk Beef Cttle Report, pp ) indictes tht extending stlk grzing by 10% would reduce wintering costs nd increse profit/hed by $1.00. Without tking the clves completely through growing/finishing system, it is not possible to determine the optimum level of WCGF supplementtion on corn residue. However, these dt indicte wht gins might be expected with different levels of WCGF supplementtion. About 3.5 lb DM/dy is needed to meet the protein nd phosphorus requirements of the clves. Therefore, it is logicl to feed t lest tht mount. Bsed on the nonliner nlysis, it seems tht 6.0 lb DM/ dy is logicl upper limit. This rnge of feeding should result in gins rnging from lb/dy. Producers my then select level of WCGF bsed on desired dily gin, stlk vilbility, cttle frme nd weight (s it ffects mrket weight), nd length of summer grzing seson. 1 D. J. Jordon, reserch technicin; Terry Klopfenstein, professor; Todd Milton, ssistnt professor, Animl Science, Lincoln. Impct of Grzing Corn Stlks in the Spring on Crop Yields Glen Erickson Terry Klopfenstein D.J. Jordon Wlker Luedtke Gry Lesoing 1,2 Grzing corn residue in the spring hd no detrimentl effect on subsequent soyben yields nd my slightly increse yields. Summry A two-yer experiment ws designed to determine the impct of grzing corn residue during the spring on subsequent soyben yields in cornsoyben rottion. Tillge tretments consisting of ridge-till, fll-till, springtill, nd no-till were lso evluted to determine if yields could be mintined by lleviting compction from grzing in the spring. Grzing tretments overll, nd specificlly in the ridge-till nd no-till systems, resulted in incresed yields. Residue cover ws lso more sensitive to chnges in tillge rther thn grzing; however, both tretments decresed residue cover. Introduction Trditionl corn residue grzing occurs from November to Februry. Bsed on numerous reserch trils t the University of Nebrsk Agriculturl Reserch nd Development Center, grzing corn residue during this period does not impct subsequent crop yields, whether corn or soybens (1997 Nebrsk Beef Report, pp ). While grzing corn residues decreses residue nd increses bulk density of soil, presumbly no impct is observed, becuse cttle were only mintined in crop fields while the ground ws frozen (1997 Nebrsk Beef Report, pp ). However, producers require both holding res nd feed sources for cttle from Februry until pstures re vilble in lte April. Fields generlly re very wet nd not frozen from Februry to April. Therefore, compction from cttle my cuse detrimentl yield losses in subsequent crops. The objective of this study ws to determine the impct from grzing corn residue from lte Februry until lte April on subsequent soyben yields. Procedure In 1997, 90-cre field ws identified. The field ws split into qurters with ungrzed check strips replicted cross ech qurter. Crop production ws bsed on n nnul corn-soyben rottion with one-hlf of the field grown to ech crop. The field ws irrigted by liner-move (2425 feet width) irrigtion system (Vlmont, Vlley, Neb.) nd the grzing res replicted within ech hlf grown to corn for grzing experiments. The grzing trils were conducted from Febr. 25 until April 14 in 1998 (48 dys) nd from Mrch 1 until April 26 in 1999 (56 dys). Animls were fed supplement dily t 1.5 lb per hed per dy. Clf stocking rte ws pproximtely.8 cres per clf for 60 dys. The stocking rte ws bsed on verge stocking rtes to optimize niml performnce. Some producers my use spring grzing res s holding or clving pens where stocking rtes re greter thn.8 cres per clf. Tillge tretments included ridgetilling during the summer, no-tillge, fll tillge with chisel followed by conventionl tillge (disk) in the spring, or spring conventionl tillge lone. All tillge tretments were conducted during the corn rottion with no tillge following the soyben crop. Grzed nd ungrzed tretments were superimposed on tillge tretments. The no-till, ridgetill, nd spring-till tretments ech contined grzed nd ungrzed section. Tretments were pplied to n eight-row strip nd grzing tretments mnged with electric wires. Residue cover ws mesured by determining residue t points in trnsect cross the eight-row tretment strip. At hrvest, the middle six rows were hrvested out of the 8-row strip to mintin one border row on ech side nd eliminte effects from grzing pressure nd fences. Soyben hrvest ws conducted with 3300 John Deere combine with 10-foot hed. Ech six-row strip (Continued on next pge) Pge Nebrsk Beef Report

44 ws hrvested in two psses, tking four rows first followed by two rows. After ech individul repliction (eight replictions per tretment; seven tretments) ws hrvested, totl weight ws recorded using n experimentl weigh wgon. Smples were collected t this time to determine DM nd DM yield. Corn hrvest (in 1999) ws conducted with norml production equipment nd ll eight rows included in the repliction. Weighing nd smpling were performed similr to soybens except Brent 550 bu grin crt with J-str lod cells ws used for weighing. Results Animl performnce Clf performnce ws vrible cross yers (Tble 1). In 1998, clves gined 2.12 lb per dy. In 1999, ADG ws significntly less nd clves just mintined weight during the 56 dys (ADG = -.1lb per dy). In 1998, clves were lighter, with initil weights of 612 lb s compred to 688 lb in However, finl weights were not significntly different between yers. When compring performnce bsed on field mngement, whether no-till or ridgetill, performnce ws not influenced (P >.70) nd initil nd finl weights were similr. Gins were different cross yers bsed on residul corn grin in fields. In 1998, residul grin estimtion from surrounding fields suggested tht n verge of 15 bu of corn grin per cre Tble 1. Animl performnce of clves grzing corn residue in the spring. ws vilble to clves. In 1999, no corn grin ws vilble bsed on residul grin mesurements. Crop production Tillge tretment b Soyben yields the following fll fter spring grzing were influenced by tretments (P <.01). Soyben yields on the grzed no-till res tended to be greter thn the ungrzed no-till nd ungrzed ridge-till tretments (P <.20). Yield on the ridge-till grzed re ws greter (P <.05) thn ll other tretments except the no-till grzed tretment (P >.40). Grzing from pproximtely Febr. 20 until April 20 did not depress soyben yields s ws our originl hypothesis. Bsed on these results, grzing improved subsequent soyben yields in the ridge-till nd no-till mngement systems. Our hypothesis ws tht yields would potentilly be depressed, but tillge tretments might help llevite yield depressions due to soil compction from spring grzing. Bsed on these results, spring nd fll tillge cused depression in yields Yer c Item Ridge-till No-till SE Initil weight, lb Finl weight, lb ADG, lb Stocking rtes were pproximtely 1 clf per cre cross tillge tretments nd yers. b No effect of tillge tretment ws observed (P >.70). c Significnt yer effect ws observed for IW nd ADG (P <.05). reltive to ridge-till nd no-till grzed tretments. Corn residue ws influenced by both grzing nd tillge tretments (Tble 2). Bsed on mesurements before grzing nd fter grzing, corn residue decresed in ll tretments including ungrzed res. In ungrzed res, residue cover decresed by 13 to 18%. Fll tillge nd spring tillge decresed residue s ws expected. Fll tillge resulted in much lower initil cover (38%) nd ws lowest the following spring with only 23% cover. The no-till grzed tretment resulted in 27% decrese nd ridge-till grzing led to 37% reduction in cover. Spring tillge (following grzing) decresed cover by pproximtely 55% for both grzed nd ungrzed tretments. The tillge tretments pper to hve much lrger impcts on residue cover thn grzing; however, both mngement fctors decrese cover. Due to the unstructured tretment design, contrsts were used to distinguish differences between tretment groups. Tble 3 illustrtes contrsts used nd sttistics for soyben yield nd Tble 2. Effect of spring grzing nd tillge tretments on residue cover before nd fter grzing nd soyben yields the following fll. Tillge: b Ridge Ridge None Fll/Spring Spring Spring None Grzing: GR UG UG UG UG GR GR Tretment: Item c SE F-test Yield (lb) 329 d 319 e,f 318 e,f 314 f 316 f 319 e,f 326 d,e Yield (bu/cre) 59.3 d 57.3 e,f 57.2 e,f 56.5 f 56.9 f 57.2 e,f 58.5 d,e Residue-B, % 82.5 d 83.7 d,e 90.2 e 37.8 f 89.4 e 86.9 e 89.5 e Residue-A, % 50.0 d 72.6 e 81.6 f 22.6 g 36.9 h 36.9 h 65.5 e Chnge, % 37.0 d 16.9 e 13.2 e 18.4 e,f 56.1 g 53.6 g 26.5 f No significnt yer by tretment interction ws observed (P >.90). Yields were determined from 16 plots per tretment (8 plots per yer) tht rnged from.07 to.12 cres. b Tillge tretments included ridge-till, no-till, fll tillge, nd spring tillge. Superimposed on those were grzing (GR) nd ungrzed (UG) tretments. c Soyben yield mesured in lb of DM nd bushels per cre on 90% ir-dry bsis, percent residue cover before (B) grzing nd fter fll tillge, percent residue cover fter (A) grzing nd spring tillge, nd the chnge from before grzing to fter in % cover by subtrction. Residue mesurements fter grzing nd the subsequent chnge in residue re bsed on 1998 only. d,e,f,g,h Mens within row with unlike superscripts differ (P <.10) Nebrsk Beef Report Pge 44

45 Tble 3. Grzing nd tillge impcts on soyben yields nd residue cover. Yield (bu/cre) Residue chnge (%) Contrst Tretments P= mens P= mens Grzed vs Ungrzed 1,6,7 vs 2,3,4, vs vs 26.1 Ridge vs No-till 1,2 vs 3, vs vs 18.3 Spring-till vs No-till 5,6 vs 3, vs vs 18.3 No-till UG vs Tillge UG 3 vs 4, vs vs 37.2 Ridge GR vs Ridge UG 1 vs vs vs 16.9 No-till GR vs No-till UG 7 vs vs vs 13.2 Tretment numbers re: 1=Ridge-till grzed, 2=Ridge-till ungrzed, 3=No till ungrzed, 4=Fll/Spring till ungrzed, 5=Spring till ungrzed, 6=Spring till grzed, nd 7=No till grzed. chnge in residue cover. Compring grzed to ungrzed tretments verged cross tillge tretments suggests grzing increses (P <.01) soyben yields by 1.5 bu per cre. Grzing corn residue in the spring lso incresed the mount of residue loss from 26 to 38%. Seprting effect of grzing within ridge-till suggests grzing incresed (P <.04) yields by 2.0 bu per cre. Grzing corn residue in the spring with no-till mngement tended (P <.14) to increse soyben yields s well. Bsed on the comprisons of ridge-till nd fll/spring tillge with no-tillge, tillge did not influence soyben yields. Tillge nd grzing both incresed losses of residue cover over no-tillge nd ungrzed tretments. Corn yields two yers fter grzing in Februry of 1998, nd hrvesting bens in the fll of 1998 were recorded in No significnt yield differences were observed. In summry, spring corn residue grzing ppers to hve no detrimentl impcts on subsequent soyben yields. Yields were sttisticlly higher in grzed no-till nd ridge-till tretments thn the other tretments. Fll nd spring tillge tretments hd little impct on yields. Residue cover ppers to be effected more by tillge tretments thn grzing. Tillge lso ppers to msk ny grzing effects on corn residue cover. 1 Glen Erickson, grdute student, D.J. Jordon, reserch technicin, Terry Klopfenstein, professor, Animl Science, Lincoln; Wlker Luedtke, reserch coordintor, Agriculturl Reserch nd Development Center, Med; Gry Lesoing, former reserch ssistnt professor, Center for Sustinble Agriculturl Systems, Lincoln 2 This mteril is bsed upon work supported by the Coopertive Stte Reserch, Eduction, nd Extension Service, U.S. Dept. of Agriculture, under Agreement No Any opinions, findings, conclusions, or recommendtions expressed in this publiction re those of the uthors nd do not necessrily reflect the view of the USDA. Economic Returns of Wet Byproducts s Cttle Feed Richrd Perrin Terry Klopfenstein 1 Feeding wet byproducts from grin processors to cttle hs grown in Nebrsk until over million tons re now being fed, with net benefits of over $42 million per yer. Summry Reserch t the University of Nebrsk nd other institutions hs demonstrted the fesibility of feeding corn sweetener/ethnol industry byproducts directly to cttle in wet form, rther thn mrketing them s dried feeds. Using combintion of experimentl results, survey dt nd mrket prices, the verge vlue of these wet feed products ws bout $130 per ton of dry mtter during the 1990s, compred to their lterntive vlue s dried feed of $93 per ton. Given the mounts fed, the nnul net benefits of this innovtion in Nebrsk grew from bout $1 million in 1992 to n nnul verge of bout $42 million during Introduction Due to new technologies nd mple irrigtion resources, Nebrsk s grin production grew fster thn ny other mjor producing stte during the 1970s nd 1980s. The reltively chep grin tht resulted ws fctor tht both encourged cttle feeding (to the extent tht during the sme period Nebrsk went from fifth to second lrgest cttle feeding stte) nd ttrcted grin processing plnts (Nebrsk cpcity for producing corn sweeteners nd ethnol grew fster thn ny other stte in the pst decde). A second fctor importnt in ttrcting corn processing plnts ws the reserch demonstrting tht processing byproducts cn be fed directly to the expnding numbers of finishing cttle, rther thn being dried nd shipped to distnt mrkets. The study reported here is n evlution of the direct economic benefit of the innovtion of feeding wet byproducts directly to finishing cttle, rther thn further processing them for the dried feed mrket. The experimentl work t the University of Nebrsk nd elsewhere hs estblished the possibilities for substituting wet corn gluten feed, wet distillers grins nd steep liquor for other feeds in beef cttle feedlots. The pproch of this study is to estimte the feed vlue of these byproducts (the vlue of the feeds for which they substitute) nd to subtrct from tht, the vlue of the byproducts in their next best use, which is their vlue s dried feeds (Continued on next pge) Pge Nebrsk Beef Report

46 djusted for drying costs. This is mesure of the net benefit of the innovtion of feeding unit of the mteril in wet form rther thn dry. We use survey dt nd plnt production estimtes to estimte the totl mount of such feeds fed. We lso exmine the distribution of benefits between the processor nd the cttle feeder, which depends upon the price chrged for the byproducts. Procedure The imputed vlue of byproduct feed (the shdow price of the feed) ws determined from the results of 18 different experiments (or sets of experiments) s the chnge in the cost of other feed inputs per pound of beef produced, divided by the number of pounds of byproduct fed per pound of beef. This in turn depends upon the prices of lterntive feeds nd cn be represented s: V j = imputed vlue per pound of the j-th byproduct fed = 1 c = i j p i 1 x i x j τ x j τ = i j β ij p i, where β ij = 1 τ i τ Here x i represents pounds of feed i (dry mtter bsis) fed per pound of gin, c is feed cost per pound of gin, x i / τ the mount in stndrd rtion minus tht in wet byproducts rtion, p i the price of feed i (dry mtter bsis here), nd β i j is the pounds of dry mtter of feed i for which pound of byproduct j substitutes. For those experiments which included multiple wet byproduct x j Tble 1. Wet byproduct feed vlue coefficients, per ton of byproduct dry mtter. Feed vlue coefficient (β ij ) b Avg price Wet distillers Wet gluten Feed ingredient nd units per unit grins feed Steep liquor Alflf hy, per ton $ Alflf silge, per ton $ Corn cobs, per ton $ Corn silge, per ton $ Dry rolled corn, per bushel $ Liquid 32, per cwt $ Molsses, per cwt $ Soyben mel, per ton $ Suppl, per ton $ Ure, per ton $ Other, per ton $ Averge imputed vlue $ $ $ to 99. b Per unit of ingredient, rther thn per pound of dry mtter. rtions, we considered only tht byproduct rtion tht provided the lowest cost per pound of gin. The imputed vlue of wet byproduct feeds s determined by the bove procedure will vry from yer to yer s the vlue of substituted feeds chnge. To determine the net benefit of feeding the byproduct in wet form, the estimted opportunity cost of selling the feed s dried byproduct subtrcted from the imputed vlue ws estimted. This opportunity cost for given yer ws the mrket price of the dried feed less n estimted $20 per ton of dry mtter for drying cost. Finlly, to clculte the distribution of this net benefit between cttle feeder nd processor, we used the verge delivered price of wet byproducts, s determined from survey responses from 183 feedlot opertors in Nebrsk. Finlly, to estimte the totl benefits of the wet feeding innovtion in Nebrsk, we obtined estimtes from the Nebrsk Ethnol Bord of the mount of grin processed by Nebrsk plnts, nd from this we estimted the totl mount of byproducts fed in wet form by Nebrsk cttle feeders, from 1992 through Results Tble 1 summrizes the vlue coefficients for the three wet byproducts, expressed in terms of units of trditionl ingredients (units s specified in the tble) for which one ton of wet byproduct substituted in the experiments. One ton of dry mtter in wet distillers grins, for exmple, substituted for.03 tons of lflf hy, 49.8 bushels of dry rolled corn, etc, which hd totl vlue of $ per ton, when these trditionl ingredients were vlued t verge prices. The imputed vlue of wet gluten feed ws somewht lower t $122.81, while tht for steep liquor ws somewht higher t $ Tble 2 summrizes our estimtes of Tble 2. Summry of vlue nd benefits per ton DM of wet byproduct fed from Wet distillers grin Wet gluten feed Steep liquor Feed Deliv. Opp. Totl Feed Deliv. Opp. Totl Feed Deliv. Opp. Totl vlue price cost benefit vlue price cost benefit vlue price cost benefit Avg Nebrsk Beef Report Pge 46

47 Tble 3. Quntity fed nd economic benefits of wet byproduct feeds in Nebrsk from Wet distillers grins Quntity (1,000 tons DM) Benefit ($1,000,000) $0.00 $0.00 $1.37 $5.69 $2.17 $4.77 $ Wet corn gluten feed Quntity (1,000 tons DM) Benefit ($1,000,000) $0.56 $7.09 $9.00 $26.55 $15.66 $38.21 $22.46 $20.30 Steep liquor Quntity (1,000 tons DM) Benefit ($1,000,000) $0.40 $3.60 $4.37 $5.27 $4.07 $6.81 $5.26 $3.95 All byproduct feeds Quntity (1,000 tons DM) Benefit ($1,000,000) $0.96 $10.69 $14.74 $37.51 $21.90 $49.78 $41.94 $34.51 the net economic benefit of the wet byproduct feeding innovtion. The bottom line indictes the verge feed vlue of wet distillers grin ws $140 per ton, while the opportunity cost s dried feed ws $118 per ton, for n verge net benefit of $22 per ton. Delivered price verged $107, indicting n verge gin of $32 per ton to feeders, nd $10 per ton loss to processors. Over the pst two yers processors hve obtined positive $5.77/ton benefit. It ppers processors sold wet grins lower thn the opportunity cost in order to estblish the mrket during the first few yers. Conversely, corn gluten feed ws mrketed bove the opportunity cost beginning in The benefit to the processors hs been $8.14 per ton nd the benefit to producers hs been $ In Tble 3 we summrize our estimtes of the quntities of byproduct feeds fed in Nebrsk, nd the totl net benefits generted ccording to the estimted vlues per ton s reported in Tble 2. As of 1992, the mount of byproducts fed ws negligible, but by 1997 the mount fed hd grown to over million tons, with n estimted net benefit of nerly $50 million. Currently, 30% of the benefits re from distillers grins from the dry milling industry nd 70% from the wet milling industry which produces corn gluten feed nd steep liquor. 1 Richrd Perrin, professor, Agriculturl Economics; Terry Klopfenstein, professor, Animl Science. Urinry Allntoin Excretion of Finishing Steers: Effects of Grin Adpttion nd Wet Milling Byproduct Feeding Ryn Mss D.J. Jordon Todd Milton Terry Klopfenstein Rick Stock 1 Steep liquor nd distillers solubles do not stimulte microbil crude protein supply, s mesured by llntoin excretion. Rumen ph correlted with microbil crude protein supply. Summry A metbolism tril investigted microbil protein supply for finishing cttle. In Phse I, cttle were dpted to dry-rolled corn diet. Urinry llntoin excretion ws positively correlted with TDN supply. In Phse II, cttle were fed tht diet or diets with portion of the corn replced by one of two levels of the corn wet milling byproducts steep liquor or distillers solubles. Byproducts inclusion did not increse microbil crude protein supply, s mesured by urinry llntoin excretion. Rumen ph lso correlted with microbil crude protein supply. Introduction Corn wet milling plnts often blend corn steep liquor (STEEP) nd distillers solubles (DS) together, mking it impossible to differentite if one or both ingredients cuse performnce response. A possible explntion for response my be stimultion of microbil crude protein supply (MCP) due to mino cids nd peptides present in STEEP nd/or DS. Urinry llntoin excretion is non-invsive mrker of MCP supply (see relted beef report rticle). The objectives of our reserch were to: 1) mke estimtes of urinry llntoin excretion s mrker of MCP supply for beef cttle fed dry-rolled corn bsed finishing diets; nd 2) test the hypothesis STEEP nd/or DS stimulte MCP synthesis when they replce dryrolled corn in finishing diets. (Continued on next pge) Pge Nebrsk Beef Report

48 Procedure Five crossbred yerling steers (men wt = 775 lbs.) were fitted with rumen cnnuls ccording to the guidelines of the UNL Institutionl Animl Cre nd Use Committee. Cttle were housed in 10' x 10' box stlls, fed every two hours vi utomtic feeders, nd llowed d libitum ccess to feed. The tril ws conducted in two phses: common grin dpttion phse (Phse I) nd 5 x 5 Ltin squre (Phse II). In Phse I, cttle were dpted to dry-rolled corn bsed finishing diet by feeding diets consisting of 45, 35, 25, 15, nd 7.5% lflf for 4, 4, 7, 7, nd 7 dys, respectively. Dry-rolled corn replced lflf in those dpttion steps. In Phse II, ech period of the 5 x 5 Ltin squre ws 21 dys. All diets contined 7.5% cobs s the roughge source nd were blnced to 15.3% CP using ure (this is the CP concentrtion of the 15% STEEP tretment). Tretments were: 1) CONT = 92.5% dry-rolled corn plus dry supplement; 2) 7.5% STEEP; 3) 15.0% STEEP; 4) 7.5% DS; nd 5) 15.0% DS. In tretments two through five, the byproducts replced dry-rolled corn in the rtion. In Phse I, cttle were tethered continuously to fcilitte urine collection by bdominl funnels ttched to vcuum pump. Although urine ws collected continuously in Phse I, urine volume ws mesured nd liquots were sved for nlysis on the lst four dys of ech dpttion step only. In Phse II, cttle were llowed to move freely in their stlls on dys 1 through 17 nd were tethered for urine collection on dys 18 through 21. Aliquots of urine were nlyzed for llntoin. Dily dry mtter intke ws mesured in both phses nd rumen ph ws mesured every three hours during dys of ech period of Phse II. The following were estimted for ech steer nd grin dpttion step combintion in Phse I: verge dily dry mtter intke nd verge dily llntoin excretion in the urine. The following estimtes were mde for ech steer nd period combintion in Phse II: verge dily dry mtter intke, verge dily Tble 1. Dry mtter intkes nd urinry llntoin excretion of cttle during Phse I, the grin dpttion phse. Steps Item b SEM DMI, lb/dy Allntoin, mmol/dy Cttle were dpted to dry-rolled corn bsed finishing diet in five steps: 45, 35, 25, 15, nd 7.5% lflf for 4, 7, 7, 7, nd 7 dys, respectively. b Ech number is the men of ll five nimls, except for Step 5 (one niml went off feed becuse of blown rumen cnnul). Tble 2. Dry mtter intkes, dily rumen ph, nd urinry llntoin excretion of cttle during Phse II. Diets Item CONT 7.5STEEP 15STEEP 7.5DS 15DS SEM DMI, lb/dy Rumen ph b Allntoin, mmol/dy c Dry-rolled corn finishing diet (CONT) blnced to 15.3% CP with ure (if needed). In ll other tretments, by-product (STEEP = steep liquor; DS = distillers solubles) replced dry-rolled corn t the percentge of DM indicted. b Orthogonl contrst for CONT vs. verge of other four tretments (P =.32). c Orthogonl contrst for CONT vs. verge of other four tretments (P =.05). rumen ph nd verge dily llntoin excretion in the urine. Results Dry mtter intke nd urinry llntoin excretion dt for Phse I re shown in Tble 1. Becuse grin dpttion step is confounded with time, no test of sttisticl difference cn be mde. However, the dt serve s useful observtion of the trend llntoin excretion follows s cttle re dpted to dry-rolled corn finishing diet. As lflf hy is replced in the diet by dry-rolled corn, the totl mount of llntoin excretion increses. This is intuitively correct becuse the totl DMI remined reltively constnt while the mount of dry-rolled corn incresed. Therefore, the mount of TDN vilble for rumen fermenttion incresed, resulting in greter mount of MCP supply. These dt re the only known estimtes of urinry llntoin excretion by cttle during grin dpttion period. Dt for Phse II re shown in Tble 2. There were no differences in DMI. Averge dily rumen ph ws numericlly lower for the verge of the wet milling byproducts versus the control (P =.30). The power of the test of rumen ph ws compromised becuse there ws filure to obtin rumen ph dt on two of the five periods in the Ltin squre. From these dt, one could only speculte s to the possible cuse of reduced rumen ph by wet milling byproducts; however, the ph of those feed ingredients my provide n explntion of the trend. The ph of the steep liquor nd distillers solubles fed in this tril were 4.22 nd 4.96, respectively. Previous reserch with the byproducts shows they contin lctic cid nd significnt mount of cette, propionte nd butyrte. These cids would certinly lower the ph of the feedstuffs. Allntoin excretion ws lower (P =.05) for the verge of the wet milling byproducts versus the control. These dt refute our hypothesis tht one or both of these byproducts my stimulte MCP supply. Rumen ph ws correlted (r 2 =.61) with llntoin excretion (Figure 1). This is in greement with the 1996 NRC Model of Nutrient Requirements for Beef Cttle. In the reserch cited in the NRC, bcteril cultures were grown in vitro nd ph ws mnipulted, resulting in lower MCP s ph declined. The dt provide support for the concept 2001 Nebrsk Beef Report Pge 48

49 Allntoin excretion mmol/dy y = x R 2 = Rumen ph of ph sensitivity of rumen microbes in prcticl feeding conditions. We conclude tht steep liquor nd distillers solubles do not stimulte MCP supply. When verged together, these byproducts reduced MCP supply, probbly becuse of trend towrd lower rumen ph. The performnce response of finishing cttle fed the wet milling byproducts steep liquor nd distillers solubles cnnot be explined by incresed MCP supply. Figure 1. Urine llntoin excretion versus rumen ph of cttle fed vrious dry-rolled corn finishing diets (inclusion of wet-milling byproducts vries). 1 Ryn Mss, grdute student; D.J. Jordon, technicin; Todd Milton nd Terry Klopfenstein, ssistnt professor nd professor; UNL niml science, Lincoln. Rick Stock, Crgill Corn Milling, Blir, NE. Progrmmed Gin Finishing Systems In Yerling Steers Fed Dry-rolled Corn Or Wet Corn Gluten Feed Finishing Diets Tony Scott Todd Milton Terry Klopfenstein 1 Progrmming gin during the first 100 dys of 161-dy finishing period resulted in reduced cumultive performnce compred to d libitum feeding. Summry One hundred sixty crossbred yerling steers were used in completely rndomized design to determine the response to progrmmed gin finishing system in diets with nd without wet corn gluten feed. Including progrmmed gin phse in the finishing period reduced dily gin, hot crcss weight, ft thickness nd mrbling score in diets with nd without wet corn gluten feed. Diets contining wet corn gluten feed incresed dily gin, hot crcss weight nd ft thickness compred with diets contining only dryrolled corn. Progrmming gin improved efficiency but reduced net return per niml nd incresed cost of gin versus d libitum feeding. Introduction Improvements in feed efficiency hve been demonstrted with feeding systems designed to control feed intke in feedlot cttle; however, dily gin my decrese, resulting in incresed dys on feed. There re mny methods tht cn be used to control feed intke, one of which is n pproch referred to s progrmmed gin. Progrmmed feeding techniques re systems in which the net energy equtions re used to clculte the mount of feed required to chieve predetermined rte of gin. Bsed on the diet being fed, progrmmed rte of gin is selected nd the mount of feed required to chieve the progrmmed rte of gin cn be clculted. The interest in progrmmed gin feeding systems hs been incresed by reports tht similr dily gins, hot crcss weights nd dys on feed cn be chieved with progrmmed gin feeding systems when compred to d libitum feeding. At the sme time, reductions in the mount of feed consumed result in improvements in efficiency. However, two previous studies (1999 Nebrsk Beef Report, pp 46-48; 2000 Nebrsk Beef Report, pp 41-43) conducted t the University of Nebrsk to determine the effects of progrmmed gin feeding strtegies filed to observe significnt improvement in feed efficiency while both dily gins nd hot crcss weights were lower s result of using progrmmed gin feeding system. Both of the previously conducted studies included wet corn gluten feed in the finishing diet. The objective of this study ws to determine if the response to progrmmed gin feeding system differed in finishing diets with nd without wet corn gluten feed. Procedure One hundred sixty crossbred yerling steers (643 lb) were strtified by weight (Continued on next pge) Pge Nebrsk Beef Report

50 nd rndomly ssigned to one of 16 pens (10 hed/pen). Ech pen ws rndomly ssigned to one of four tretments with 2x2 fctoril tretment structure. Tretment fctors were: d libitum feeding system (AL) or progrmmed gin feeding system (PG); nd dry-rolled corn finishing diet (DRC) or wet corn gluten feed finishing diet (WCGF). Pens ssigned to PG were trgeted to gin 3.0 lb/d for d 1-50 nd 3.4 lb/d for d On dy 101, pens ssigned to PG were llowed to consume feed AL for the reminder of the tril. Feed intkes required to chieve the progrmmed rtes of gin were clculted using the net energy equtions contined in the NRC (1996) computer model nd were djusted every seven dys. The finl diets (Tble 1) were formulted to contin minimum of 13.5% CP,.70% C,.35% P, nd.65% K, nd contined 27g/ton Rumensin nd 10 g/ton Tyln (DM bsis). Steers were implnted with Synovex -C on d 1 nd reimplnted with Synovex -Plus on d 50. Steers were slughtered t commercil pcking plnt when the AL control groups were visully estimted to hve reched.45 in of ft over the 12th rib. Following 24-h chill, USDA yield grde, mrbling score nd 12th rib ft thickness were recorded. Finl weights were clculted by djusting hot crcss weights to common dressing percentge (63%). Net return nd cost of gin for ech pen were clculted using Nebrsk 10-yer verge prices for feedstuffs, feeder cttle nd slughter cttle. Wet corn gluten feed ws priced t 93% the price of corn. Results Performnce during the PG period (d 1-100) is presented in Tble 2. There ws significnt (P<.05) feeding system x finishing diet interction for DMI during d By design, DMI of both PG tretments were similr nd significntly less thn either AL tretment. However, in steers offered feed AL, feeding WCGF incresed DMI significntly versus feeding DRC. Dily gin ws not ffected by PG; however, feeding WCGF incresed (P<.10) dily gin when compred to feeding DRC. A significnt Tble 1. Composition of finishing diets (100% DM bsis). Ingredient DRC WCGF Dry-rolled corn Wet corn gluten feed 35.0 Alflf hy Sorghum silge Soyben mel 4.0 Molsses 3.0 Supplement Finely ground grin sorghum Limestone Ure.685 Slt Diclcium phosphte.100 Potssium chloride Trce minerl Rumensin Vitmin premix Tyln DRC = dry-rolled corn; WCGF = wet corn gluten feed. Tble 2. Effect of progrmmed gin (PG) nd finishing diet (DRC or WCGF) on progrmmed gin period performnce (d 1-100). Tretment DRC WCGF AL PG AL PG SEM DMI, lb/dy b f e g e.32 ADG, lb c Feed:gin bd 5.9 e 4.5 f 6.4 e 4.0 g DRC = dry-rolled corn; WCGF = wet corn gluten feed; AL = d libitum; PG = progrmmed gin. b Feeding system x finishing diet interction (P<.05). c Finishing diet effect (P<.10). d Anlyzed s gin:feed. efg Mens within row with unlike superscripts differ (P<.10). Tble 3. Effect of progrmmed gin (PG) nd finishing diet (DRC or WCGF) on cumultive performnce nd crcss chrcteristics. Tretment DRC WCGF Ad Lib PG Ad Lib PG SEM Dys on feed Initil wt., lb DMI, lb/dy b i k h j.31 Totl feed, lb/hd b 3708 i 3155 j 4124 h 3273 j 49 ADG, lb cd Feed:gin be 6.0 i 5.8 i 6.3 h 5.6 j Hot crcss wt, lb cd Mrbling score ce Ft thickness, in. cd Net return, $/hed cdf Cost of gin, $/cwt cdf DRC = dry-rolled corn; WCGF = wet corn gluten feed; AL = d libitum; PG = progrmmed gin. b Feeding system x finishing diet interction (P<.05). c Feeding system effect (P<.05). d Finishing diet effect (P<.10). e Anlyzed s gin:feed. f Mrbling score: 400 = Slight 0; 450 = Slight 50; 500 = Smll 0. g Vlues used in clcultions: cttle purchse price = $81.00/cwt; cttle sles price = $108.00/cwt hot crcss; yrdge = $0.30/d; feed cost = $108.58/ton (DRC) nd $97.02/ton (WCGF); interest on cttle nd 1/2 feed = 10%. hijk Mens within row with unlike superscripts differ (P<.10) Nebrsk Beef Report Pge 50

51 (P<.05) feeding system x finishing diet interction ws observed for feed conversion. Feed conversion ws improved in both PG tretment groups irrespective of diet when compred with AL. Additionlly, feed efficiency of the PG/WCGF tretment group ws improved versus ll other tretments. Cumultive performnce nd crcss dt re presented in Tble 3. All steers were fed for 161 dys. There ws significnt (P<.05) feeding system x finishing diet interction for DMI relted to the mgnitude of the difference between ech AL control group nd its PG counterprt. When feeding DRC, PG reduced intke by 3.43 lb/d. However, the difference when feeding WCGF ws 5.29 lb/d. The reltionship for the totl mount of feed consumed throughout the tril responded similrly. There were significnt min effects of both feeding system (P<.05) nd finishing diet (P<.10) for dily gin. Feeding WCGF incresed dily gin while the PG feeding system reduced dily gin. There ws significnt (P<.05) feeding system x finishing diet interction for feed conversion similr to tht observed for both dry mtter intke nd totl feed consumed. When feeding DRC, PG improved feed conversion 2.4% nd the two feeding systems were not sttisticlly different. However, when feeding WCGF, efficiency ws improved 11.9% in the PG feeding system. There were min effects of both feeding system (P<.05) nd finishing diet (P<.10) for hot crcss weight. Feeding WCGF incresed hot crcss weight while the PG feeding system decresed hot crcss weight. The PG feeding system significntly reduced (P<.05) mrbling score. There were significnt min effects for both feeding system (P<.05) nd finishing diet (P<.10) for 12th rib ft thickness. Feeding WCGF incresed ft thickness while the PG feeding system reduced ft thickness. Net return ws incresed (P<.10) by feeding WCGF nd ws reduced (P<.05) by the PG feeding system. Similrly, cost of gin ws reduced (P<.10) when feeding WCGF nd incresed (P<.05) by the PG feeding system. These dt indicte tht including progrmmed gin phse in the finishing system reduced both dily gin nd profitbility. Regrdless of diet, feeding cttle d libitum ws strongly fvored in this tril when compred to the progrmmed gin finishing system. However, there my be differences in the observed efficiency response to progrmmed gin finishing systems mong finishing diets tht differ in composition. 1 Tony Scott, reserch technicin, Animl Science, Lincoln; Todd Milton, ssistnt professor, Animl Science, Lincoln; Terry Klopfenstein, professor, Animl Science, Lincoln. Economic Evlution of Corn Processing for Finishing Cttle Rob Cooper Todd Milton Terry Klopfenstein Dick Clrk 1 Economics of high-moisture corn re highly dependent on the discount t which it is purchsed to dry corn. Economics of stem-flked corn re ttrctive t corn prices common in Nebrsk. Summry A finishing tril ws conducted to determine performnce of steers fed dry-rolled, high-moisture nd stemflked corn-bsed diets. High-moisture corn nd stem-flked corn were determined to hve 100% nd 108% the vlue of dry-rolled corn, respectively. Estimted costs of corn processing ($/ton) rnged from $1.44 to $1.60 for dry-rolled corn, $1.98 to $2.34 for high-moisture corn, nd $6.79 to $7.16 for stem-flked corn. Economics of high-moisture corn re dependent on the discount t which it is purchsed to dry corn. Economics of stem-flked corn re dependent on corn price, but pper ttrctive t prices common in Nebrsk. Introduction The cttle feeding industry in the United Sttes commonly processes corn to some degree before it is incorported into rtion nd delivered to the niml. The gol of most processing methods is to increse strch vilbility of corn, thereby incresing its vlue to the niml. Corn processing cn vry in methodology, cost nd effectiveness in incresing vlue. Dry rolling, high moisture nd stem flking re the most common forms of corn processing in feedyrds tody. High moisture nd stem flking re more costly thn dry rolling, but n increse in cttle performnce my offset these costs. Objectives of this evlution were to determine economic return of high-moisture nd stem-flked corn reltive to dry-rolled corn in diets for finishing cttle. Performnce Procedure Ninety crossbred yerling steers (612 lb) were used in completely rndomized design with 3 x 5 fctoril tretment structure to evlute effect of corn processing on performnce of (Continued on next pge) Pge Nebrsk Beef Report

52 finishing cttle. Steers were rndomly ssigned to one of three finishing diets (Tble 1) which were bsed on dryrolled (DRC), high-moisture (HMC), or stem-flked corn (SFC). Within ech diet, steers were rndomly ssigned to one of five levels of ure (0,.5, 1.0, 1.5, or 2.0% of dietry DM). Steers were individully fed using Cln electronic gtes. Steers were offered their respective finishing diet on dy 1 t 1.8% of body weight (DM bsis). Feed offered then ws incresed.5 lb per dy (DM bsis) until steers were d libitum (pproximtely 21 dys). Steers were weighed initilly on three consecutive dys fter being limit-fed t 2.0% of body weight for five dys in order to minimize differences in gut fill. Steers were implnted with Synovex C on dy 1, reimplnted with Synovex Plus on dy 67, nd fed for totl of 167 dys. Finl weights were clculted using hot crcss weights djusted to common dress (63%). Dt were nlyzed using Mixed procedure of SAS. Lest squre mens were seprted using the Lest Significnce Difference method. Tble 1. Composition of finishing diets (% of DM). Diet Ingredient DRC HMC SFC Dry rolled corn 82.0 High moisture corn b 82.0 Stem flked corn c 82.0 Alflf hy Cottonseed hulls Molsses Dry supplement d DRC = dry-rolled corn, HMC = high-moisture corn, SFC = stem-flked corn. b High-moisture ws rolled t hrvest nd stored in covered concrete bunker nd ws 29% moisture nd 46% soluble protein t time of tril. c Stem-flked corn ws processed to 29 lb/bushel flke weight t commercil feedyrd fcility nd huled to reserch feedlot on weekly bsis. d All diets supplemented to contin minimum of.7% C,.28% P,.6% K, nd.15% S (DM bsis). All diets contined 27 g/ton Rumensin nd 10 g/ ton Tyln (DM bsis). processing in the performnce dt. Costs of processing. There re four primry costs ssocited with corn processing: initil costs of equipment, electricity, nturl gs nd diesel fuel. Avilble literture ws reviewed to estimte these costs. Initil costs of equipment re difficult to estimte becuse they cn be extremely vrible depending on the type of system nd vilble resources. Costs reported in literture (Schke et l Energy nd economic evlution of corn nd sorghum processing. Texs Agriculturl Experiment Sttion, pp. 1-12) were used for this evlution; however, reders should substitute costs which more ccurtely reflect their own sitution. In the report mentioned bove, initil equipment costs ($/hed feedyrd cpcity) ssocited with DRC, HMC, nd SFC for 5,000 nd 20,000 hed feedyrds were estimted (Tble 2). No ttempt ws mde to updte these costs for infltion becuse we were unsure how much costs on $/hed bsis hve chnged. For this discussion, equipment ws deprecited over 10-yer period, ssuming no slvge vlue, nd interest (10%) ws chrged on the verge vlue of the investment. Energy costs of corn processing re primrily composed of electricity, nturl gs nd diesel fuel usge (Tble 2). Electricl usge ws ssumed to be Economics Economics of corn processing re dependent on both vlue chnge in corn s well s cost of processing. Informtion regrding both of these fctors is discussed below. It is importnt to note tht mny ssumptions re mde in this economic evlution. Although ssumptions re believed ccurte given vilble informtion, reders re encourged to substitute vlues tht more ccurtely reflect their own sitution. Vlue of processing. The best indictor of vlue chnge due to corn processing is cttle performnce. For this discussion, it will be ssumed tht chnge in feed conversion is directly relted to chnge in vlue of corn. Therefore, if feed/gin is improved by 10% by processing method, the corn hs 10% more vlue. This pproch hs limittions, but seems conservtive nd strightforwrd. This pproch is conservtive becuse corn does not comprise 100% of the diet. All chnges in vlue in this discussion re reltive to DRC becuse it is the simplest form of Tble 2. Costs of corn processing for 5,000 nd 20,000 hed feedyrds. Processing Method DRC HMC SFC Item 5,000 20,000 5,000 20,000 5,000 20,000 Equipment costs Initil investment, $/hd b Initil investment, $ 85, , , , , ,800 Annul deprecition, $ c 8,535 26,300 16,695 49,360 15,960 45,480 Annul interest, $ d 4,268 13,150 8,348 24,680 7,980 22,740 Annul costs, $ e 12,803 39,450 25,043 74,040 23,940 68,220 Annul corn usge, ton f 18,250 73,000 18,250 73,000 18,250 73,000 Equipment costs, $/ton g Energy costs Electricity, kwh/ton Nturl gs, mcf/ton Diesel, gl/ton Electricity, $/ton h Nturl gs, $/ton h Diesel, $/ton h Energy costs, $/ton Totl processing costs, $/ton i DRC = dry-rolled corn, HMC = high-moisture corn, SFC = stem-flked corn. b Source: 1981 Texs Agriculturl Experiment Sttion, pp c Assumes 10-yer deprecition period nd no slvge vlue. d Assumes 10% interest rte on verge investment. e Annul costs = nnul deprecition + nnul interest. f Assumes 100% cpcity nd 20 lb/dy corn intke (15% moisture bsis). g Equipment costs = nnul equipment costs divided by nnul corn usge. h Electricity = $.05/kwh, nturl gs = $4.50/mcf, diesel = $1.31/gl. i Totl processing costs = equipment costs + energy costs Nebrsk Beef Report Pge 52

53 Tble 3. Performnce of finishing cttle fed dry-rolled, high-moisture, or stem-flked corn. Processing Method DRC HMC SFC Dry mtter intke, lb/dy 22.2 b 21.6 b 20.3 c Averge dily gin, lb Feed/gin 6.13 b 6.10 b 5.62 c Feed/gin, % of DRC DRC = dry-rolled corn diet, HMC = high-moisture corn diet, SFC = stem-flked corn diet. bc Mens in sme row with unlike superscripts differ (P <.001). Return Above DRC ($/ton) y = 0.08x Commodity Corn Price ($/ton) Figure 1. Economic return of stem-flked corn bove dry-rolled corn (DRC) for 5,000 hed feedyrd. similr mong processing methods (17.9 kwh/ton) nd priced t $.05/kwh. Nturl gs usge for stem flking ws ssumed to be 1.1 mcf/ton of corn processed nd priced t $4.50/mcf which reflects current costs in Nebrsk. Diesel fuel usge of.05 gl/ton of corn processed ws ssumed for high-moisture corn for pcking in bunker silo nd use of front-end loder while feeding. Diesel fuel ws priced t $1.31/gl, which ws the 12-month verge price in Nebrsk for Totl estimted processing costs for DRC, HMC, nd SFC in 5,000 nd 20,000 hed feedyrds re shown in Tble 2. High-moisture corn nd SFC were nlyzed by their return bove DRC, becuse DRC ws the simplest form of processing in performnce dt. Return of either HMC or SFC bove DRC ws clculted by the eqution: Return of processing bove DRC ($/ton) = [((corn price, $/ton) + (cost of dry rolling, $/ton)) x (% improvement in feed/ gin)] - [(corn price, $/ton) + (cost of respective processing, $/ton)]. Results Results from the finishing tril re shown in Tble 3. Corn processing method x ure level interctions were detected for DM intke (P <.05) nd ADG (P <.05), but not for feed/gin (P >.10). Becuse feed/gin is the mesurement of interest for this evlution, only min effects of corn processing re shown in Tble 4. Steers fed SFC consumed pproximtely 7.3% less DM (P <.01) thn steers fed DRC nd HMC diets. Dily gins were similr (P >.50) for ll diets. As result, steers consuming the SFC diet were 8% more efficient (P <.001) thn steers consuming DRC or HMC diets. Results from the performnce tril re in close greement with those reported in literture. A recent review of grin processing summrized performnce from 353 reserch trils in which DRC, HMC, nd/or SFC were fed. In this report, feed/gin ws similr for steers consuming DRC nd HMC, wheres steers consuming SFC were bout 11% more efficient (1997 Journl of Animl Science, 55: ). Bsed on results from the finishing tril nd clcultions described bove, HMC hs 100% the vlue of DRC, wheres SFC hs 108% the vlue of DRC. Therefore, if DRC costs $2.00/bu, then HMC lso is worth $2.00/bu, wheres SFC is worth $2.16/bu. It is importnt to note tht these vlues re ll on n equl DM bsis. In ddition, these vlues do not ccount for fctors such s: buying high-moisture corn t discount compred to dry corn, differences in shrink mong the processing types nd differences in interest on purchsed corn. High-moisture corn hs 100% the vlue of DRC (equl DM bsis). Given cost ssumptions described bove, HMC would result in $.74/ton loss in 5,000 hd feedyrd compred to DRC. Wheres in 20,000 hd feedyrd, HMC would result in $.54/ton loss compred to DRC. These vlues re ll on n equl DM bsis nd ssume the sme commodity corn price. Therefore, purchse of HMC would need to be discounted by these mounts, plus costs of ny dditionl shrink nd interest which my occur, in order to brek even with DRC. There re severl wys in which feedyrds discount purchse price of HMC. One wy might be $.02/bu discount per point of moisture bove 15%. Therefore, if feedyrd purchses corn t 28% moisture, commodity price would be discounted by $.26/bu. At the 10-yer verge Nebrsk commodity corn price ($2.48/bu), HMC would be purchsed t $2.22/bu (15% moisture bsis). This would result in $8.55/ton return for HMC bove DRC in 5,000-hed feedyrd. Agin, this vlue does not ccount for ny dditionl shrink or interest which my occur with HMC. Stem-flked corn hs 108% the vlue of DRC (equl DM bsis). Figure 1 shows economic return bove dry rolling for SFC in 5,000-hed feedyrd t vrious price levels for commodity corn. Regression eqution (y = mx - b) is given so tht ctul return bove dry rolling cn be clculted t ny corn price, where: y = return bove dry rolling ($/ton), m = slope of line, x = commodity corn price ($/ton), b = intercept). The regression line for 20,000-hed feedyrd (y =.08x (Continued on next pge) Pge Nebrsk Beef Report

54 ) ws not displyed becuse it ws not visully distinguishble from the 5,000-hed feedyrd line. Corn price t which SFC breks even with DRC cn be determined by setting y equl to zero nd solving for x. For 5,000-hed feedyrd, corn price would need to be t lest $67.91/ton ($1.90/bu) in order for SFC to brek even with DRC. For 20,000-hed feedyrd, corn price would need to be t lest $65.37/ton ($1.83/bu) for SFC to brek even with DRC. At 10- yer verge commodity corn price for Nebrsk ($2.48/bu; $88.57/ton), SFC would return $30,167 per yer bove DRC ($1.65/ton on 18,250 ton/yer) in 5,000-hed feedyrd. In 20,000-hed feedyrd, SFC would return $135,510 per yer bove DRC ($1.86/ton on 73,000 ton/yer). These clcultions ssume 100% cpcity, 20 lb/dy corn intke (15% moisture bsis) nd do not ccount for differences in shrink, moisture pprecition, or lbor between DRC nd SFC. Economics of HMC re gretly dependent on the mgnitude of discount t which it is purchsed compred to dry corn. Clerly, the lrgest cost ssocited with HMC is the initil investment in concrete bunker. Highmoisture corn cn be economiclly ttrctive to feedyrd if the discount t which it is purchsed is greter thn dditionl processing costs, shrink nd interest bove DRC. This probbly vries somewht from feedyrd to feedyrd. Economics of SFC pper to be more clerly defined given ssumptions mde in this report. Economics of SFC re highly dependent on commodity corn price, but pper to brekeven t corn price well below the 10-yer verge, even in reltively smll 5,000-hed feedyrd. 1 Rob Cooper, reserch technicin; Terry Klopfenstein, professor; Todd Milton, ssistnt professor, Animl Science, Lincoln; Dick Clrk, professor, West Centrl Reserch nd Extension Center, North Pltte. Effect of Corn Processing on Degrdble Intke Protein Requirement of Finishing Cttle Rob Cooper Todd Milton Terry Klopfenstein Doug Jordon 1 Degrdble intke protein requirement of finishing cttle is ffected by method of corn processing nd presumbly rte nd extent of ruminl strch fermenttion. Summry Three finishing trils were conducted to determine effect of corn processing on degrdble intke protein requirement of feedlot cttle. Finishing diets consisted of 82% processed corn which ws either dry rolled, high moisture, or stem flked. Degrdble intke protein levels were chieved by dding 0 to 2.0% ure (DM bsis) to the control diets. Estimtes of degrdble intke protein requirement for dry-rolled corn-bsed diet were pproximtely 6.3% of dietry DM. Degrdble intke protein requirement for high-moisture corn-bsed diets ws pproximtely 10% of dietry DM. Degrdble intke protein requirement for stem-flked cornbsed diet ws between 7 nd 9.5% of dietry DM. Introduction Degrdble intke protein (DIP) is the frction of feed crude protein which is vilble to the microbil popultion. In typicl diets for finishing cttle, DIP is composed of both degrdble true protein nd non-protein nitrogen. A deficiency in DIP would hve two effects. First, DIP deficiency would lower microbil crude protein production, possibly resulting in metbolizble protein (MP) deficiency if sufficient UIP ws not supplemented. Second, DIP deficiency would reduce energy yield from crbohydrte fermenttion, thereby lowering voltile ftty cid production nd energetic efficiency of the diet. Therefore, deficiency in DIP my led to reduced finishing performnce even when the niml s metbolizble protein requirement hs been met. Level 1 of the 1996 NRC model predicts tht DIP requirement for typicl dry-rolled corn-bsed finishing diet is pproximtely 6.8% of dietry DM. Few dt exist tht directly evlute the effect of corn processing on DIP requirement. Averge ruminl strch digestibilities of 78, 89 nd 83% for dry-rolled, highmoisture nd stem-flked corn hve been reported. It is our hypothesis tht grin processing methods which increse rte nd extent of strch fermenttion my increse the dietry DIP requirement reltive to dry-rolled corn. Objectives of these experiments were to determine DIP requirements of finishing cttle fed dry-rolled, high-moisture nd stem-flked corn-bsed finishing diets. Tril 1 Procedure Two hundred nd fifty-two crossbred yerling steers (834 lb) were used in rndomized complete block design to determine DIP requirement of finishing steers fed high-moisture corn-bsed diet. Steers were split into three initil weight blocks nd rndomly ssigned to one of 12 pens nd to one of four dietry tretments (21 steers per pen, 3 pens per tretment). Dietry tretments consisted of four levels of dietry DIP tht were ccomplished by dding 0,.4,.8, or 1.2% ure to the bse diet (DM bsis) Nebrsk Beef Report Pge 54

55 High-moisture corn-bsed finishing diet (HMC) is shown in Tble 1, while dietry crude protein nd DIP vlues re shown in Tble 2. High-moisture corn ws hrvested t pproximtely 29% moisture, processed through rollermill, nd stored in covered concrete bunker. Steers were dpted to finishing diet in 21 dys using lflf hy to replce high-moisture corn (50% lflf for 3 dys, 40% of 4 dys, 30% for 7 dys, nd 20% for 7 dys, DM bsis). Cottonseed hulls were only included in the finishing diet. Steers were weighed initilly on two consecutive dys fter being limit-fed t 2% of body weight for 5 dys in order to minimize differences in gut fill. Steers were implnted with Synovex Plus on dy 1 nd fed for 108 dys. Finl weights were clculted using hot crcss weights djusted to common dress (63%). Dt Tble 1. Composition of finishing diets (% of DM). Diet Ingredient DRC HMC SFC Dry-rolled corn 82.0 High-moisture corn 82.0 Stem-flked corn 82.0 Alflf hy Cottonseed hulls Molsses Dry supplement b DRC = dry-rolled corn, HMC = high-moisture corn, SFC = stem-flked corn. b All diets supplemented to contin minimum of.7% C,.28% P,.6% K, nd.15% S (DM bsis). All diets contined 27 g/ton Rumensin nd 10 g/ton Tyln (DM bsis). were nlyzed using liner, qudrtic nd cubic contrsts. Nonliner nlysis of feed/gin ws used to predict the DIP requirement. Tril 2 Two hundred nd sixty-four crossbred yerling steers (781 lb) were used in completely rndomized design to determine DIP requirement of finishing steers fed stem-flked corn-bsed diet. Steers were strtified by initil weight to one of 24 pens (11 steers per pen). Pens were rndomly ssigned to one of six dietry tretments (4 pens per tretment). Tretments consisted of six levels of dietry DIP which were ccomplished by dding 0,.4,.8, 1.2, 1.6, or 2.0% ure to the bse diet (DM bsis). Stem-flked corn-bsed finishing diet (SFC) is shown in Tble 1, while dietry crude protein nd DIP vlues re shown in Tble 3. Stem-flked corn ws processed to flke density of 29 lb/bushel t commercil feedlot fcility nd huled to the reserch feedlot on weekly bsis. Steers were dpted to finishing diet in 21 dys using lflf hy to replce stem-flked corn (40% lflf for three dys, 30% of four dys, 20% for seven dys nd 10% for seven dys, DM bsis). Cottonseed hulls were included t 5% of DM in ll diets. Steers were weighed initilly on two consecutive dys fter being limit-fed t 2% of body weight for five dys to minimize differences in gut fill. Steers were implnted with Synovex C on dy Tble 2. Dietry protein composition nd finishing performnce for high moisture corn-bsed diet (Tril 1). Tretment Ure, % of DM SEM Crude protein, % of DM DIP, % of DM DIP blnce, g/dy MP blnce, g/dy DM intke, lb Dily gin, lb b Feed/gin b Ft depth, in c Mrbling score bd Bsed on NRC tbulr vlues. b Liner (P <.03). c Liner (P =.06). d 400 = Trces 0, 500 = Smll 0, 600 = Modest 0. 1, reimplnted with Revlor S on dy 47 nd fed for totl of 129 dys. Finl weights were clculted using hot crcss weights djusted to common dress (63%). Dt were nlyzed using liner, qudrtic nd cubic contrsts. Nonliner nlysis of feed/gin ws used to predict the DIP requirement. Tril 3 Ninety crossbred yerling steers (612 lb) were used in completely rndomized design with 3 x 5 fctoril tretment structure to evlute effect of corn processing on DIP requirement of finishing cttle. Steers were rndomly ssigned to one of three finishing diets which were bsed on DRC, HMC, or SFC (Tble 1). Within ech diet, steers were rndomly ssigned to five levels of dietry DIP which were ccomplished by dding 0,.5, 1.0, 1.5, or 2.0% ure to the bse diet (DM bsis). Dietry CP nd DIP vlues re shown in Tble 4. Highmoisture corn nd stem-flked corn were similr to Trils 1 nd 2, respectively, while dry-rolled corn ws processed so tht prticle size ws s corse s possible with reltively few whole kernels pssing through the rolls. Idelly, kernels were broken into pproximtely four pieces. Steers were individully fed using Cln electronic gtes. Steers were dpted to their respective finishing diet over n pproximtely 21-dy period. Steers were offered their respective finishing diet on dy 1 t 1.8% of body weight (DM bsis). Feed offered then ws incresed.5 lb per dy (DM bsis) until steers were d libitum. Steers were weighed initilly on three consecutive dys fter being limit-fed t 2.0% of body weight for five dys in order to minimize differences in gut fill. Steers were implnted with Synovex C on dy 1, reimplnted with Synovex Plus on dy 67, nd fed for totl of 167 dys. Finl weights were clculted using hot crcss weights djusted to common dress (63%). Dt were nlyzed using Lest Significnce Difference method nd liner, qudrtic nd cubic contrsts. Nonliner nlyses of feed/gin were used to predict DIP requirements. (Continued on next pge) Pge Nebrsk Beef Report

56 Tril 1 Results Effects of DIP level on performnce of finishing steers fed high-moisture corn-bsed diet re shown in Tble 2. Dry mtter intke ws not ffected (P =.75) by dietry DIP nd verged 26.8 lb/dy. However, both verge dily gin nd feed/gin improved linerly (P <.03) s dietry DIP incresed. Nonliner nlysis of feed/gin predicted tht the DIP requirement would be met by 1.1% ure (95% confidence intervl ws from 1.0 to 2.2%), which would provide dietry DIP level of 10.2%. We hypothesized tht DIP requirement for high-moisture corn-bsed diet would be greter thn 7.1% of dietry DM s predicted by 1996 NRC. However, we did not expect the requirement to be s high s 10.2% of dietry DM. This level of DIP is greter thn is commonly fed in high moisture corn-bsed diets. Tril 2 Effect of DIP level on performnce of finishing steers fed stem-flked corn-bsed diet re shown in Tble 3. Dry mtter intke responded qudrticlly (P =.01) s dietry DIP incresed. In ddition, verge dily gin nd feed/gin lso responded qudrticlly (P <.0001) s dietry DIP incresed. Nonliner nlysis of feed/gin predicted brekpoint t.8% ure (95% confidence intervl ws.79 to.88%). This dietry ure concentrtion would provide dietry DIP vlue of pproximtely 7.1%. Level 1 of 1996 NRC model predicted tht the DIP requirement would be met t 7.1% of DM. Tble 3. Dietry protein composition nd finishing performnce for stem flked corn-bsed diet (Tril 2). Tretment Ure, % of DM SEM Crude protein, % of DM DIP, % of DM DIP blnce, g/dy MP blnce, g/dy DM intke, lb b Dily gin, lb c Feed/gin c Ft depth, in d Mrbling score de Bsed on NRC tbulr vlues. b Qudrtic (P =.01). c Qudrtic (P <.001). d Qudrtic (P <.10). e 400 = Trces 0, 500 = Smll 0, 600 = Modest 0. Tble 4. Dietry protein composition nd finishing performnce for Tril 3. Tretment Ure, % of DM SEM Crude protein, % of DM b DIP, % of DM b DRC HMC SFC DM intke, lb/dy DRC 21.8 c c.8 HMC 23.0 c d.8 SFC f 17.8 d e.8 Dily gin, lb/dy DRC g 3.39 c 3.61 cd 3.38 c c.14 HMC h 3.70 c 3.45 c 3.51 cd d.14 SFC f 2.99 d 3.79 d 3.72 d cd.14 Feed/gin DRC c 5.88 c 6.17 c.22 HMC cd 5.81 cd 6.25 c.22 SFC g d 5.38 d 5.38 d.22 Ft depth, in Mrbling score i DRC = dry-rolled corn, HMC = high-moisture corn, SFC = stem-flked corn. b Bsed on NRC tbulr vlues. cde Mens with unlike superscript within column differ (P <.10). f Qudrtic effect of ure level (P <.05). g Liner effect of ure level (P <.05). h Cubic effect of ure level (P <.05). i 500 = Smll 0, 600 = Modest 0. Tril 3 Effects of DIP level on performnce of finishing steers fed dry-rolled, highmoisture, nd stem-flked corn-bsed diets re shown in Tble 4. Processing method x ure level interctions were found (P <.01) for DM intke nd dily gin. Simple effects for feed/gin re lso shown in Tble 4, lthough no interction ws noted (P =.34). For DRC, dry mtter intke (P =.08) nd verge dily gin (P =.03) responded linerly with DIP level. However, feed/gin ws not ffected (P >.50) by DIP level. Nonliner nlysis of feed/gin did not predict brekpoint suggesting tht the DIP requirement ws met by the first increment of ure. In the HMC diet, dry mtter intke ws not ffected (P >.10), while verge dily gin responded cubiclly (P =.03) with DIP level. Feed/gin ws not ffected (P >.10). Nonliner nlysis of feed/gin predicted brekpoint t 1.1% ure. This level of ure suggests tht dietry DIP requirement for HMC is pproximtely 10% of dietry DM, which grees well with results from Tril 1. In the SFC diet, dry mtter intke nd verge dily gin responded qudrticlly (P <.001) with DIP level. Feed/ gin responded linerly (P =.007) with DIP level. Nonliner nlysis of feed/ 2001 Nebrsk Beef Report Pge 56

57 gin predicted brekpoint t 1.6% ure (95% confidence intervl ws 1.55 to 1.66%). This level of ure suggests tht dietry DIP requirement for SFC-bsed diet is pproximtely 9.5% of dietry DM. Degrdble intke protein requirement for DRC-bsed diets could not be determined by nonliner nlysis becuse the first increment of ure provided the best feed/gin. This suggests tht the DIP requirement for the DRCbsed diet ws met t 6.3% of dietry DM. Degrdble intke protein requirement for HMC ws consistent between Trils 1 nd 3 (pproximtely 10% of dietry DM) nd considerbly higher thn predicted level (7.1% of DM). The greter DIP requirement for HMC is most likely due to greter rte nd extent of strch fermenttion with HMC compred to DRC. Degrdble intke protein requirement for SFC ws the sme s predicted in Tril 2 (7.1% of DM), but higher in Tril 3 (9.5% of DM). Resons for differences in estimted DIP requirement for SFC-bsed diet re not cler, but my be due to differences in initil weight, intke, nd/or method of grin dpttion. Our results suggest tht the verge dietry DIP requirements for DRC, HMC, nd SFC-bsed diets re 6.3, 10.0, nd 8.3% of DM, respectively. These dietry DIP requirements re highly relted to ruminl strch digestibilities reported in literture (78, 89, nd 83% for DRC, HMC, nd SFC, respectively). Level 1 of the NRC (1996) ccurtely predicts the DIP requirement for DRC-bsed diet. However, DIP requirements for HMC nd SFC-bsed diets re underestimted becuse Level 1 of the NRC does not ccount for differences in ruminl strch digestion. Level 2 of the NRC (1996) ccounts for differences in ruminl strch digestion, nd therefore, my more ccurtely predict DIP requirements for HMC nd SFC-bsed diets. 1 Rob Cooper, reserch technicin; Todd Milton, ssistnt professor; Terry Klopfenstein, professor; Doug Jordon, reserch technicin, Animl Science, Lincoln. High Moisture nd Dry-Rolled High-Oil Corn for Finishing Feedlot Steers Wnd Cerkoney Terry Mder Fred Owens 1 When fed in the dry rolled form, high-oil corn improved feed efficiency over norml corn. However, high-oil corn did not improve efficiency over norml corn when fed in the high moisture form. Summry Finishing steers fed diets contining dry-rolled high-oil corn hd 2.5% reduction in dry mtter intke nd 4.2% better feed efficiency thn steers fed diets contining dry-rolled norml corn. Hot crcss weight, dressing percent, liver bscess score, rib ft thickness, mrbling score nd yield grde did not differ mong tretments. Steers fed high-moisture high-oil corn hd lrger ribeye re nd greter percent kidney, pelvic nd hert ft thn steers fed high moisture norml corn. No differences in performnce or efficiency were detected from substituting high-oil high moisture corn for norml high moisture corn. Introduction Nutritionlly modified grin vrieties, such s high-oil (HO) corn, hve been developed tht my improve efficiency of livestock production. Higher oil content of grin increses energy density of the diet nd ids in dust control. However, the idel mngement systems (processing method; ft, ionophore, minerl supplementtion) for nutritionlly modified grins my differ from those idel for norml grin. For exmple, South Dkot Stte University reserchers detected processing by corn type interction between norml nd high-oil corn. Dry mtter intkes nd gins were 5 to 10% greter for steers fed rolled HO corn thn steers fed whole HO corn. These results indicte tht HO corn my need to be processed prior to feeding to finishing beef cttle. To dte, no informtion hs been published on HO corn hrvested, stored nd fed s high moisture grin to feedlot cttle. The objective of this study ws to evlute high-oil corn versus norml corn when fed s dry-rolled or high moisture grin to finishing feedlot steers. Procedure In seprte loctions, norml (N) nd high-oil (HO) corn vrieties were plnted t the University of Nebrsk, Northest Reserch nd Extension Center in Concord, Neb. Vrieties were hrvested s both high-moisture (HM) nd s dry corn. At hrvest ech lod of corn ws smpled nd nlyzed for DM content. High-oil nd norml high moisture corn were hrvested t 28 % DM. Corn hrvested s HM grin ws rolled nd stored in two seprte bunker silos. Dry corn (D) ws corsely rolled prior to feeding. Three hundred eighty British x continentl crossbred steers were purchsed in erly November 1998 nd were processed in mid- to lte November. Processing included: weighing, implnting, tgging, vccinting, nd deworming. Weights t processing were used to divide the steers into light (LWG) nd hevy (HWG) weight groups. On Dec. 7, the LWG gin ws weighed nd sorted by weight into dditionl groups nd plced into their respective tril pens on Dec. 8. Initil weight for the LWG ws n verge of full live weights tken on Dec. 7 nd Dec. 8. The HWG ws treted the sme s the LWG, with full live weights tken (Continued on next pge) Pge Nebrsk Beef Report

58 Tble 1. Percentge of grin from ech grin type nd form in ech diet. Tretment Grin type Norml Dry-rolled High moisture High-oil Dry-rolled High moisture on Dec. 9 nd Dec. 10. Fifteen steers were excluded from the reserch pool for the following resons: too hevy, too light, or lme. The LWG included 200 steers with 10 steers/pen in 20 pens (five weight groups with four tretments in ech weight group). The HWG included 160 steers with 10 steers/pen (four weight groups with four tretments in ech weight group). Pens were ssigned rndomly within ech weight group to one of four tretments. Ech diet contined equl mounts of DM corn from D nd HM. This mde the four different combintions of N nd HO corn in the D nd HM form: (1) ND plus NHM, (2) HOD plus HOHM, (3) HOD plus NHM, nd (4) ND plus HOHM s shown in Tble 1. On DM bsis, the finishing diets contined 84% corn, 7.5% lflf hy, 4.5% liquid supplement, 2.0% soyben mel, nd 2.0% Rumensin, Tyln, thimine supplement. Diet ingredients nd feedbunk smples were obtined every second week nd nlyzed for DM content. Corn smples were lso nlyzed for CP, pepsin insoluble nitrogen nd crude ft. High-moisture corn ws lso nlyzed for ph, ethnol nd selected voltile ftty cids. Feedbunk smples were nlyzed for nitrogen, clcium nd phosphorus. Fecl smples were collected from two steers/pen nd four pens/ tretment nd nlyzed for ph, crude ft, nd strch content. The LWG nd HWG were hrvested fter 92 nd 81 dys on feed, respectively. On dy of hrvest, liver bscess scores nd hot crcss weights were recorded. After 24-hour chill, rib eye re (REA), rib ft thickness (RF), USDA qulity grde, USDA yield grde nd percent kidney, pelvic nd hert ft (% KPH) were recorded. Tissue smples Tble 2. Corn nlysis, Dry Mtter Bsis. Norml High-oil P <.10 High Moisture Corn Dry mtter t hrvest, % Dry mtter t feeding, % Crude ft, % ph Crude protein, % Pepsin insoluble nitrogen, % NS Ethnol, % NS Lctte, % Acette, % NS Propionte, % NS Dry-Rolled Corn Dry mtter, % NS Crude ft, % Pepsin insoluble nitrogen, % NS Tble 3. Summry of steer performnce, intke nd efficiency compring high moisture nd dry-rolled high-oil corn over pproximtely 90 dy feeding period. Tretment Item No. hed No. pens Initil weight, lb Averge dily gin, lb/dy DM intke (DMI), lb/dy b Feed efficiency, DMI/gin c Finl weight, lb Adjusted to common dress of 63%. b Tretments 1 plus 4 vs 2 plus 3 differ (P <.10). c Tretments 1 plus 4 vs 2 plus 3 differ (P <.05). Tble 4. Summry of steer crcss dt compring high moisture nd dry-rolled high-oil corn in feedlot diets. Tretment Item Hot crcss weight, lb Actul dress, % KPH ft, % of crcss Ribeye re, sq in Estimted ft, in Mrbling score b USDA yield grde Finl yield grde c Liver bscesses, % Tretments 1 plus 3 vs 2 plus 4 differ (P <.05). b Mrbling score of 400 = Trces, 500 = Smll, 600 = Modest, 700 = Moderte. c Finl yield grde = (2.50 x estimted ft thickness) + (.20 x percent KPH) + (.0038 x hot crcss weight) (.32 x ribeye re). were removed from the neck region of sub-smple of crcsses (men of 20 crcsses/tretment) of the HWG on the dy crcss dt ws collected. Lipid extrcted from both the len nd ft tissue were nlyzed for following ftty cids: myristic, myristoleic, plmitic, plmitoleic, steric, oleic, linoleic, linolenic, rchidic, ecosenoic, nd summed to clculte totl sturted, nd mono-, di-, nd tri-unsturted. Results Even though HOHM corn nd NHM corn were hrvested t the sme moisture content, HOHM corn hd higher (P <.05) DM content (bsed on oven 2001 Nebrsk Beef Report Pge 58

59 DM determintions) thn NHM corn fter fermenttion (Tble 2). The CP content ws greter (P <.10) for HO corn thn N corn s is typicl for high-oil corn (Tble 2). Bsed on nlysis of feces from these steers, no differences (P >.05) in fecl strch content were detected mong tretments. However, crude ft content of feces ws 5.04%, 7.96%, 6.85%, nd 6.31% for tretments 1, 2, 3 nd 4 respectively. Thus steers fed HODR corn (tretments 2 nd 3) hd more (P <.05) of their fecl DM s crude ft thn steers fed NDR corn (tretments 1 nd 4). When compred with steers fed diets contining dry-rolled norml corn, (men of tretments 1 nd 4) steers fed diets contining HODR corn (men of tretments 2 nd 3) tended to hve lower (P <.10) dry mtter intkes but hd improved (P <.05) feed conversions. No differences (P >.10) were detected in feed intke, gin nd efficiency between steer groups fed high-moisture norml corn (men of tretments 1 nd 3) vs high-moisture high-oil corn (men of tretments 2 nd 4; Tble 3). No differences (P >.05) in sturtion of ftty cid from len or ft tissue mong tretments were detected. However, steers fed high-oil corn tended to hve greter (P <.10) percentges of rchidic cid (C20:0) in both met (.66 vs.59) nd ft (.92 vs.86) smples. Steers fed high-oil high-moisture grin hd greter (P <.05) internl (KPH) ft thn steers fed norml high moisture grin (2.35 vs 2.30). Feeding mixture of high-oil grin with norml corn grin (men of tretments 3 nd 4) tended to slightly increse (P <.10) the incidence of liver bscesses when compred to steers fed either grin form lone (verge of tretments 1 nd 2; Tble 4). Results from this study indicte tht substituting dry high-oil corn for portion of the dry corn with norml oil content in diets for feedlot steers cn decrese dry mtter intke nd improve feed conversion. Although no problems with fermenttion of high-moisture high-oil corn were encountered, no performnce dvntge from substituting high-moisture high-oil corn for highmoisture corn with norml oil content ws detected. 1 Wnd Cerkoney. reserch technicin, Terry Mder, professor, Animl Science, Northest Reserch nd Extension Center, Concord; Fred Owens, Optimum Qulity Grins, L.L.C., Des Moines, IA. Corn Processing Method in Finishing Diets Contining Wet Corn Gluten Feed Tony Scott Todd Milton Terry Klopfenstein Rick Stock 1 Feed efficiency nd dietry net energy vilble for gin tended to be improved by more intensively processing corn in finishing diets contining wet corn gluten feed. Summry Two trils were conducted to determine the effects on performnce nd crcss chrcteristics of corn grin diets differing in degree of processing nd contining wet corn gluten feed. Generlly, more intensive processing methods such s fine-grinding, high moisture ensiling, nd stem-flking resulted in lower dily feed consumption compred to feeding rolled or whole corn. Feed efficiency nd dietry net energy concentrtion tended to be improved by more intensive processing methods in finishing diets contining wet corn gluten feed. Introduction Inclusion of wet corn gluten feed in plce of corn grin replces dietry strch with highly digestible fiber. The resultnt effect cn be incresed feed intke nd dily gin s well s decresed incidence nd severity of cidosis in finishing cttle. While feeding wet corn gluten feed is widely ccepted prctice, limited informtion is vilble bout the effects different grin processing methods my hve in diets contining wet corn gluten feed. The objectives of this reserch were to evlute the effects of corn processing method in finishing diets contining wet corn gluten feed nd to evlute the vlue of feeding wet corn gluten feed in miniml (dry-rolled) nd intensive (stem-flked) processed corn-bsed finishing diets on performnce nd crcss chrcteristics of finishing clves. Tril 1 Procedure Four hundred eighty crossbred steer clves (667 lb) were strtified by weight nd rndomly ssigned to one of 32 pens (15 hed/pen). Ech pen ws rndomly ssigned to one of eight tretments. Four tretments were designed bsed on dry-rolled corn (Continued on next pge) Pge Nebrsk Beef Report

60 (DRC) or stem-flked corn (SFC; 29 lb/bu) with or without replcement of corn with 32% Sweet Brn 60 wet corn gluten feed (WCGF). Also, finishing diet in which DRC replced SFC in n equl proportion to the replcement of SFC with WCGF ws fed. The three other tretments were finishing diets contining 32% WCGF (DM bsis) nd either finely ground corn (FGC), erly hrvested (30% moisture) nd rolled high-moisture corn (HMC), or whole corn (WC). Dt from ll of the tretments contining 32% WCGF were nlyzed to determine the performnce nd crcss responses to grin processing method in finishing diets contining WCGF. The cost of gin for ech tretment ws clculted with rtion cost djustments for ech grin processing method. The djustments were bsed upon the verge of the vlues reported by Cooper et l. elsewhere in this report (Economic Evlution Of Corn Processing For Finishing Cttle) with the exception of finely ground corn for which n dditionl 3% ws dded to the cost of dry-rolling nd whole corn which ws ssessed no processing chrge. The ingredient costs (s-is bsis) for corn grin ($2.49/bu), lflf hy ($60.72/ton), nd soyben mel ($209.20/ton) were bsed on 10-yer verge prices ( ) pid/ received by Nebrsk producers. Other ingredient costs were bsed on the previous yer s verge pid by the University of Nebrsk feedmill. Adpttion diets contined 45, 35, 25, nd 15% lflf hy (DM bsis). The finl diets (Tble 1) were formulted to contin minimum of 13.4% CP,.70% C,.35% P, nd.65% K, nd contined 27 g/ton Rumensin nd 10 g/ton Tyln (DM bsis). The supplement in diets not contining WCGF included 5% soyben mel (DM bsis) s source of nturlly degrdble protein to ensure sufficient metbolizble protein. Due to bunk mngement problems relted to the ccumultion of fines, the molsses level in the FGC diet ws incresed to 6% (DM bsis) on dy 87. Steers were implnted with Synovex -S on dy 1 nd reimplnted with Synovex -Plus on dy 87. Tble 1. Composition of Tril 1 finishing diets (100% DM bsis). Tretment DRC DRC SFC SFC DRC FGC HMC WC Ingredient WCGF WCGF SFC WGCF WCGF WCGF DRC FGC HMC SFC WC WCGF Alflf hy Molsses Supplement DRC = dry-rolled corn; FGC = finely-ground corn; HMC = high-moisture corn; SFC = stem-flked corn; WC = whole corn; WCGF = wet corn gluten feed. Tble 2. Composition of Tril 2 finishing diets (100% DM bsis). Tretment DRC DRC SFC SFC FRC HMC Ingredient WCGF WCGF WGCF WCGF DRC FRC HMC SFC WC WCGF Alflf hy Molsses Supplement DRC = dry-rolled corn; FGC = finely-rolled corn; HMC = high-moisture corn; SFC = stem-flked corn; WC = whole corn; WCGF = wet corn gluten feed. Tril 2 Two hundred eighty-eight crossbred yerling steers (888 lb) were strtified by weight nd rndomly ssigned to one of 24 pens (12 hed/pen). Ech pen ws rndomly ssigned to one of six tretments. Four tretments were designed bsed on dry-rolled corn (DRC) or stemflked corn (SFC; 29 lb/bu) with or without replcement of corn with 22% Sweet Brn 60 wet corn gluten feed (WCGF). The two other tretments were finishing diets contining 22% WCGF (DM bsis) nd either finely rolled corn (FRC) or erly hrvested (30% moisture) nd rolled high-moisture corn (HMC). Dt from ll of the tretments contining 22% WCGF were nlyzed to determine the performnce nd crcss responses to grin processing method in finishing diets contining WCGF. The cost of gin for ech tretment ws clculted with rtion cost djustments for ech grin processing method. The djustments were the sme s in Tril 1 with the exception of finely rolling corn for which n dditionl 3% ws dded to the cost of dry-rolling. Adpttion diets contined 45, 35, 25, nd 15% lflf hy (DM bsis). The finl diets (Tble 2) were formulted to contin minimum of 13.5% CP,.70% C,.35% P, nd.65% K, nd contined 27 g/ton Rumensin nd 10 g/ton Tyln (DM bsis). Supplementl protein in ll finishing diets ws supplied with ure nd soyben mel in 60:40 rtio (CP bsis). Steers were implnted with Synovex- -Plus on dy 28. In both Trils 1 nd 2, steers were fed once dily nd llowed d libitum ccess to feed nd wter. Finl weights were clculted by djusting hot crcss weights to common dressing percentge (63%). Steers were slughtered t commercil pcking plnt where cr Nebrsk Beef Report Pge 60

61 Tble 3. Effects of grin processing method nd wet corn gluten feed inclusion in finishing diets on performnce nd crcss chrcteristics (Tril 1). Tretment DRC SFC SFC DRC WCGF SFC WCGF DRC SEM Dys on feed, dys Initil wt., lb Finl wt., lb bcd DMI, lb/dy de k i k j k.22 ADG, lb cd Feed:gin f Diet NEg, Mcl/cwt cf Cost of gin, $/cwt cdfg Hot crcss wt, lb cd Mrbling score ch Percent Choice, % Yield grde Ft thickness, in DRC = dry-rolled corn; SFC = stem-flked corn; WCGF = wet corn gluten feed. b Finl wt. = Hot crcss wt. /.63 (common dressing percentge). c Effect of WCGF (P<.10). d Effect of replcing SFC with WCGF versus DRC (P<.01). e Processing method x WCGF interction (P<.05). f Effect of grin processing method (P<.10). g Vlues used in clcultions: Rtion prices: DRC = $115.55/ton; DRC+WCGF = /ton; SFC = $119.10/ton; SFC+WCGF = $107.84/ton; SFC+DRC = ; Yrdge = $0.30/d; interest on 1/2 feed = 10%. Cttle interest not included. h Mrbling score: 500 = Smll 0 (low Choice). ijk Mens within row with unlike superscripts differ (P<.01). Tble 4. Effect of grin processing method on performnce nd crcss chrcteristics of clves fed finishing diets contining wet corn gluten feed (Tril 1). Tretment SFC HMC FGC DRC WC WCGF WCGF WCGF WCGF WCGF SEM Dys on feed, dys Initil wt., lb Finl wt., lb b DMI, lb/dy g g g f e.25 ADG, lb Feed:gin 5.18 e 5.26 ef 5.32 f 5.52 g 5.92 h Diet NEg, Mcl/cwt 70.9 h 69.8 gh 68.8 g 66.0 f 61.2 e.5 Cost of gin, $/cwt c e e e f g.23 Hot crcss wt, lb Mrbling score d Percent Choice, % Yield grde Ft thickness, in DRC = dry-rolled corn; FGC = finely-ground corn; HMC = high-moisture corn; SFC = stem-flked corn; WC = whole corn; WCGF = wet corn gluten feed. b Finl wt. = Hot crcss wt. /.63 (common dressing percentge). c Vlues used in clcultions: Rtion prices: DRC = $105.56/ton; FGC = /ton; HMC = $105.56/ ton; SFC = $107.84/ton; WC = $104.76/ton; Yrdge = $0.30/d; interest on 1/2 feed = 10%. Cttle interest not included. d Mrbling score: 500 = Smll 0 (low Choice). efgh Mens within row with unlike superscripts differ (P<.10). css dt were collected following 24-hour chill. The NEg of ech diet ws clculted using initil weight, crcss djusted finl weight, DMI nd ADG for ech pen. Tril 1 Results The performnce nd crcss dt from the DRC nd SFC tretments re presented in Tble 3. A significnt (P<.05) grin processing method x WCGF interction existed for DMI. When DRC ws fed, DMI ws incresed by 2.81 lb/dy when WCGF ws fed, wheres, when SFC ws fed, DMI ws incresed by 1.62 lb/dy when WCGF ws fed. Additionlly, the replcement of SFC with DRC resulted in significntly (P<.01) lower DMI thn replcing SFC with WCGF. Grin processing method did not ffect dily gin. However, dily gin ws incresed (P<.10) 7.7% by replcing corn grin with WCGF. Likewise, replcement of SFC with WCGF resulted in 6.5% improvement (P<.01) in dily gin compred to replcing SFC with DRC. Feed efficiency ws improved (P<.10) 5.4% when steers were fed SFC compred to DRC. Feed efficiency tended (P=.10) to be improved by feeding corn grin lone (5.24 nd 5.35 for corn grin nd WCGF, respectively). Feed efficiency ws similr when DRC or WCGF replced SFC. Dietry NEg ws 5.3% higher (P<.10) in SFC diets thn in DRC diets, while the ddition of WCGF reduced (P<.10) dietry NEg by 3.9%. There ws no difference in the dietry NEg when DRC or WCGF replced SFC. Cost of gin ws decresed (P<.10) both by feeding SFC nd by feeding WCGF. Replcement of SFC with WCGF decresed (P<.01) cost of gin compred to replcing SFC with DRC. Inclusion of WCGF in the diet incresed (P<.10) hot crcss weights. Likewise, replcement of SFC with WCGF incresed (P<.01) hot crcss weights compred to replcement of SFC with DRC. Mrbling score ws incresed (P<.10) by inclusion of WCGF compred to feeding corn grin lone. The percentge of nimls grding Choice or greter ws 75% in diets contining WCGF nd 71% in diets contining corn grin lone. Neither processing method nor replcement of SFC with DRC influenced mrbling score. Yield grde nd ft thickness were not ffected by tretment. The performnce nd crcss dt from ll diets contining 32% WGCF re presented in Tble 4. Feed (Continued on next pge) Pge Nebrsk Beef Report

62 consumption ws higher (P<.10) when feeding WC with DRC being intermedite nd FGC, HMC nd SFC being similr. Feeding WC incresed DMI by 10.8% when compred to the verge of the other four tretments. Dily gin ws similr mong the tretments. On verge, feeding SFC improved (P<.10) efficiency 7.1% compred with feeding DRC, FGC, or WC. Efficiency ws similr between clves fed SFC or HMC. Finely grinding corn improved (P<.10) efficiency compred to feeding DRC or WC. Feeding unprocessed corn (WC) in the finishing diet reduced (P<.10) feed efficiency compred with ll other tretments. Dietry NEg ws higher (P<.10) when feeding SFC compred to feeding DRC, FGC, or WC. Net energy vilble for gin ws similr when feeding SFC or HMC. Finely grinding corn improved (P<.10) dietry NEg compred to feeding DRC or WC. Cost of gin ws decresed (P<.10) by feeding FGC, HMC nd SFC compred to feeding DRC or WC. Cttle fed WC hd higher (P<.10) cost of gin thn ll other tretments. Hot crcss weight, mrbling score, yield grde nd ft thickness were not ffected by tretment. Tril 2 The performnce dt from the SFC nd DRC tretments re shown in Tble 5. A grin processing x WCGF interction (P<.10) similr to tht observed in Tril 1 ws detected for DMI. The increse in DMI observed with the ddition of WCGF to the diet ws greter when feeding DRC thn when feeding SFC (2.28 lb/dy versus 1.00 lb/dy, respectively). In ddition, cttle fed SFC lone consumed slightly more feed thn cttle fed DRC lone which contrsts with previous reserch results. Grin processing hd significnt effect (P<.10) on dily gin. Feeding SFC improved dily gin 8.1% compred to DRC. Inclusion of WCGF improved (P<.10) dily gin 7.0% compred to feeding corn grin lone. Grin processing significntly ffected (P<.10) efficiency with SFC improving efficiency 8.3% compred to DRC. Inclusion of WCGF hd no effect Tble 5. Effects of grin processing method nd wet corn gluten feed inclusion in finishing diets on performnce nd crcss chrcteristics (Tril 2). Tretment DRC SFC DRC WCGF SFC WCGF SEM Dys on feed, dys Initil wt., lb Finl wt., lb bcd DMI, lb/dy e h i h i.35 ADG, lb cd Feed:gin c Diet NEg, Mcl/cwt c Cost of gin, $/cwt cdf Hot crcss wt, lb cd Mrbling score dg Percent Choice, % Yield grde cd Ft thickness, in cd DRC = dry-rolled corn; SFC = stem-flked corn; WCGF = wet corn gluten feed. b Finl wt. = Hot crcss wt. /.63 (common dressing percentge). c Effect of grin processing method (P<.10). d Effect of WCGF (P<.10) e Processing method x WCGF interction (P<.10). f Vlues used in clcultions: Rtion prices (DM bsis): DRC = $114.38/ton; DRC+WCGF = /ton; SFC = $111.65/ton; SFC+WCGF = $110.72/ton; Yrdge = $0.30/d; interest on 1/2 feed = 10%. Cttle interest not included. g Mrbling score: 500 = Smll 0 (low Choice). hi Mens within row with unlike superscripts differ (P<.10). Tble 6.Effect of grin processing method on performnce nd crcss chrcteristics of clves fed finishing diets contining wet corn gluten feed (Tril 2). Tretment SFC HMC FRC DRC WCGF WCGF WCGF WCGF SEM Dys on feed, dys Initil wt., lb Finl wt., lb b 1341 f 1318 ef 1303 e 1310 e 9 DMI, lb/dy ADG, lb 4.22 e 4.02 f 3.95 f 3.98 f.07 Feed:gin 5.54 e 5.97 f 6.15 g 6.09 fg Diet NEg, Mcl/cwt 69.5 g 64.6 f 62.4 e 63.3 ef.8 Cost of gin, $/cwt e e f fg g.45 Hot crcss wt, lb 845 f 831 ef 821 e 826 e 6 Mrbling score d Percent Choice, % Yield grde Ft thickness, in DRC = dry-rolled corn; FRC = finely-rolled corn; HMC = high-moisture corn; SFC = stem-flked corn; WCGF = wet corn gluten feed. b Finl wt. = Hot crcss wt. /.63 (common dressing percentge). c Vlues used in clcultions: Rtion prices (DM bsis): DRC = $108.00/ton; FRC = /ton; HMC = $108.00/ton; SFC = $110.72/ton; Yrdge = $0.30/d; interest on 1/2 feed = 10%. Cttle interest not included. d Mrbling score: 500 = Smll 0 (low Choice). efg Mens within row with unlike superscripts differ (P<.10). on efficiency or dietry NEg. Feeding SFC incresed (P<.10) NEg compred to feeding DRC. Cost of gin ws decresed (P<.10) by feeding SFC nd by feeding WCGF. Feeding SFC incresed (P<.10) hot crcss weights compred to feeding DRC. Inclusion of WCGF lso incresed (P<.10) hot crcss weights compred to feeding corn grin lone. Mrbling scores were unffected by grin processing method; however, similr to Tril 1, 2001 Nebrsk Beef Report Pge 62

63 inclusion of WCGF incresed (P<.10) mrbling scores. The percentge of nimls grding Choice or greter ws 58% in diets contining WCGF nd 51% in diets contining corn grin lone. Both grin processing nd inclusion of WCGF ffected yield grde nd ft thickness. Steers fed SFC hd higher yield grdes (P<.10) nd were ftter (P<.10) thn steers fed DRC. Similrly, inclusion of WCGF incresed (P<.10) both yield grde nd ft thickness (P<.10) when compred to feeding corn grin. The performnce dt from ll diets contining 22% WCGF re presented in Tble 6. Grin tretment hd no effect on DMI. Dily gin ws improved (P<.10) 6.0% by feeding SFC compred with ll other tretments. Feeding DRC, FRC or HMC resulted in similr dily gins. Feeding SFC resulted in n 8.7% improvement (P<.10) in efficiency compred to the verge of the other tretments. Efficiency ws similr when feeding HMC or DRC; however, feeding HMC improved (P<.10) efficiency when compred to feeding FRC. Dietry NEg ws higher (P<.10) when feeding SFC compred with the other tretments. Dietry NEg ws similr when feeding DRC or HMC. Feeding HMC improved NEg compred to feeding FRC. Cost of gin ws reduced (P<.10) by feeding SFC with ll other tretments being similr. Feeding SFC incresed (P<.10) hot crcss weights compred with feeding DRC or FRC with HMC being intermedite. Other crcss chrcteristics were not ffected by tretment. The slight numericl reductions in efficiency observed in both Trils 1 nd 2 with the ddition of WCGF to DRCbsed finishing diet re in contrst to previous reserch conducted t the University of Nebrsk. In Tril 1, efficiency ws reduced 3.2% when compring DRC nd DRC with WCGF. In Tril 2, smller numericl reduction (1.2%) in efficiency ws observed. In summry of five finishing trils conducted t the University of Nebrsk from (Stock, et l., Journl of Animl Science, 2000), feeding finishing diets contining n verge of 34.8% WCGF (DM bsis; Crgill Corn Milling, Blir, NE) resulted in 5.1% improvement in efficiency. However, the dt of Scott et l. published elsewhere in this report (Progrmmed Gin Finishing Systems In Yerling Steers Fed Dry-rolled Corn Or Wet Corn Gluten Feed Finishing Diets) support the reduced efficiency response observed in this study. A 4.8% improvement in efficiency ws observed when compring DRC control diet to DRC diet contining 35% WCGF in steers offered d libitum ccess to feed. A portion of the improvement in efficiency when feeding WCGF in DRC finishing diets hs been ttributed to reduction in subcute cidosis. Therefore, possible explntion for the differing efficiency responses my be due to difference in the degree to which cidosis occurred in the respective control (DRC) groups in these studies nd tht of Scott et l. compred with those of the summry. Chnges in milling procedures my hve resulted in differences in the extent to which cidosis ws occurring. In the summry dt, double-roller mill ws used. If subcute cidosis is controlled, incresed processing of corn grin increses strch vilbility nd feed efficiency. If cidosis occurs, improved feed efficiency will not be observed in response to incresed processing of corn grin. Wet corn gluten feed hs been shown to reduce cidosis; therefore, corn-bsed finishing diets tht contin WCGF my llow corn grin to be more extensively processed without incresing the risk of cidosis. Generlly, the dt from these trils indicte tht feed conversion ws improved s the degree of processing ws incresed in diets contining WCGF. Processing methods such s stem-flking, high moisture ensiling, nd fine-grinding tended to improve efficiency when compred to either miniml processing methods (i.e., rolling) or no processing. Also, on the pen surfce, there ws significnt mount of whole corn kernels in the feces of steers fed WC nd significnt mount of whole nd lrge broken kernels in the feces of steers fed DRC. The mount of whole nd broken kernels observed on the pen surfce in the other tretments ws limited. The incresed intke observed when feeding WCGF my increse rte of pssge which would likely reduce the strch digestion of the lrge grin prticles, the consequence of which is reduced efficiency despite similr or greter dily gin. Therefore, incresing the extent to which grin is processed my improve efficiency in diets contining WCGF. These results indicte tht feeding SFC results in improved feed efficiency with or without inclusion of WCGF compred to DRC. These dt lso indicte tht grin processing methods more intensive thn dry-rolling (i.e., finegrinding, high moisture ensiling, stem-flking) cn be used to improve feed efficiency nd dietry net energy vilble for gin in finishing diets contining WCGF. 1 Tony Scott, reserch technicin, Animl Science, Lincoln; Todd Milton, djunct professor, Terry Klopfenstein, professor, nd Rick Stock, djunct professor, Animl Science, Lincoln. Pge Nebrsk Beef Report

64 Implnt Progrms for Feedlot Heifers Using Synovex Plus TM Csey Mcken Todd Milton Bill Dicke Dve McClelln Frnk Prouty 1 Implnting feedlot heifers with Synovex Plus improves ADG nd cost of gin compred to heifers implnted with Finplix-H nd fed MGA. MGA mintins crcss qulity. Summry Two commercil feedyrd experiments evluted implnt strtegies for feedlot heifers. In both experiments, implnting heifers with Synovex Plus incresed ADG compred to heifers implnted with Finplix-H nd fed MGA. In Experiment 1, implnting heifers with Synovex Plus improved feed conversion nd incresed live bsis net returns, nd the use of MGA with Synovex Plus incresed crcss merit bsis net returns nd hd similr mrbling scores compred with Finplix-H nd MGA. Introduction Growth-promoting implnts re widely used by the cttle feeding industry. Implnts cn vry in composition, dosge nd crrier. Implnts cn hve different effects on niml performnce nd crcss chrcteristics, chnging economic returns. Implnts cn hve single ctive compound s well s combintion of ctive compounds. An implnt tht is commonly used in finishing heifers is Finplix-H. Finplix-H contins 200 mg of trenbolone cette (TBA). Melengestrol cette (MGA) is routinely supplemented in feedlot heifers implnted with Finplix-H to enhnce TBA ctivity. Synovex Plus hs been recently pproved for use in finish- ing heifers. Synovex Plus is combintion implnt, contining 28 mg estrdiol benzonte (20 mg E 2 ) nd 200 mg TBA. Objectives of these trils were to: 1) compre performnce, crcss chrcteristics, nd feeding economics in heifers implnted with Synovex Plus or Finplix-H nd 2) determine if MGA supplementtion is beneficil in finishing heifers implnted with Synovex Plus. Experiment 1. Procedure Eight hundred seventy-nine heifers (726 lb) were rndomly llotted to one of three implnt progrms nd ssigned to one of 15 pens (5 replictions/tretment) on rrivl to the feedyrd. Heifers were kept seprte by truck lod-lot nd rndomly ssigned to the three implnt tretments in groups of two hed by gte sort. Within repliction, ll heifers rrived t the feedyrd t the sme time. After sorting, pens were reweighed, processed nd moved to their home pen. During processing, heifers were vccinted, treted for internl nd externl prsites, implnted with Rlgro, nd given lot-tg for identifiction. Initil weights were clculted by prorting pen weights, obtined between sorting nd processing, bck to the group s originl py weight. Hot crcss weight ws djusted to common dressing percentge of 63% to determine finl weight. Reps of heifers were reimplnted with either Synovex Plus or Finplix-H, on verge, 90 dys (rnge 84 to 101) prior to hrvest. Heifers ssigned to Finplix-H were fed MGA once they were stepped up to the finl diet (20 dys on feed). Additionlly, one Synovex Plus tretment ws fed MGA once they were stepped up to the finl diet (20 dys on feed). The finl diet contined 57.0% stem-flked corn, 16.9% dry-rolled corn, 9.1% supplement, 7.5% lflf hy, 6.5% corn steep liquor nd 3.0% ft, nd ws formulted to contin 13.6% CP, 7.0% crude ft, 0.77% C, 0.40% P nd 0.77% K. Heifers were fed n verge of 149 dys (rnge 128 to 172). All pens within repliction were hrvested under identicl conditions. Hot crcss weights were recorded on the dy of hrvest. Crcss ft thickness, mrbling score, KPH ft, longissimus muscle re nd U.S.D.A qulity grde were recorded following 24 to 36 hour chill. Performnce, crcss nd economic dt were nlyzed using the Generl Liner Model of SAS. LS Mens were used to seprte tretment differences. Additionlly, independent contrsts were used to compre: 1) the verge of Synovex Plus, with nd without MGA supplementtion, versus Finplix-H with MGA supplementtion nd 2) Synovex Plus without MGA supplementtion versus the verge of Synovex Plus nd Finplix-H when MGA ws fed. Qulity nd yield grde distributions nd the percentge of drk cutting crcsses were nlyzed using the frequency procedure (Proc Freq) of SAS. Vribles were considered significnt when probbility vlues less thn.10 were obtined. Experiment 2. Eight hundred seventy heifers (828 lb) were used in rndomized complete block design. The pen of heifers ws the experimentl unit. Six pens were used, resulting in three experimentl observtions for ech implnt tretment. Heifers were blocked by rrivl dte into the feedyrd. Heifers were processed on rrivl nd mintined in three lrge pens until reimplnting. At reimplnting, heifers were rndomly llotted to tretments by sorting individul heifers t chute-side. Thus, if the first heifer received Synovex Plus, the second heifer through the chute would hve been implnted with Finplix-H, nd so on. All heifers were fed finishing diet con Nebrsk Beef Report Pge 64

65 tining 78.0% dry-rolled corn, 11.0% corn steep liquor, 6.8% lflf hy nd 4.2% supplement, nd ws formulted to contin 13.3% CP, 4.5% crude ft, 0.75% C, 0.40% P nd 0.77% K. The finishing diet contined MGA for both tretments. Initil weights were determined on individul heifers t the time of reprocessing. Finl weights were determined by djusting hot crcss weight to common 63% dressing percentge. Heifers were slughtered t commercil pcking fcility nd crcss chrcteristics were determined following 36 to 48-hour chill. Crcss mesurements included: hot crcss weight, mrbling score, KPH ft, 12th rib ft thickness, longissimus muscle re nd U.S.D.A. qulity grde. Dt were nlyzed s rndomized complete block design using the Generl Liner Model of SAS. Tretment mens were seprted using t-test protected by significnt overll F-test. Distribution of U.S.D.A. qulity nd clculted yield grdes were nlyzed using the frequency procedure (Proc Freq) of SAS. Differences between implnt tretments were considered significnt when probbility vlues were less thn.10. Tble 1. Effect of implnt strtegy on performnce nd crcss chrcteristics in finishing heifers (Experiment 1). Implnt Strtegy SynPlus SynPlus FinH Item No MGA MGA MGA SEM b Number of pens Number of heifers Dys on feed Initil weight, lb Finl weight, lb c Dry mtter intke, lb Dily gin, lb d 3.27 e 3.35 f 3.19 g.04 Feed/gin d 5.81 h 5.74 h 6.00 i.05 Crcss weight, lb th rib ft, in. k.48 h.55 i.51 j.01 Longissimus muscle re, sq. in. l 14.3 h 14.0 hg 13.6 g.22 Clculted yield grde kl 2.44 h 2.72 i 2.80 i.08 Mrbling score klm 5.19 h 5.46 i 5.42 i.04 Qulity grde distribution n, % Prime Upper 2/3 Choice Low Choice Select Stndrd Drk cutters o, % SynPlus No MGA = Synovex Plus fed no MGA; SynPlus MGA = Synovex Plus fed MGA; FinH MGA = Finplix-H fed MGA. b SEM = Stndrd error of the men. c Finl weight clculted s hot crcss weight divided by.63 (common dressing percentge). d Contrsts of Synovex Plus tretments versus Finplix-H differ (P <.05). e,f,g Mens within row with different superscripts differ (P <.10). h,i,j Mens within row with different superscripts differ (P <.05). k Contrsts of MGA tretments versus no MGA differ (P <.05). l Contrsts of Synovex Plus tretments versus Finplix-H differ (P <.10). m Mrbling score: 4.0 = Slight; 4.5 = Slight 50; 5.0 = Smll; 5.5 Smll 50; etc. n Chi squre sttistics: Prime (P <.02); upper 2/3 Choice (P =.49); low Choice (P <.01); Select (P <.01); Stndrd (P =.27). o Chi squre sttistic (P =.13) Economic Anlysis for Experiment 1 nd 2. The economic influence of the implnt tretments ws determined using the rtion cost t the feedyrd during the period the experiment ws conducted. The rtion cost used in the nlysis includes mrkup in Experiment 1. Non-feed costs (medicine, processing, etc.) were clculted for ech pen of heifers in the experiment nd verged. This verge non-feed cost ws pplied to ech pen of heifers for clcultion of cost of gin nd net profit(loss). Finl heifer vlue ws clculted by using live price or crcss price bsed on individul heifer crcss vlue. Crcss vlue ws clculted bsed on U.S.D.A. qulity grde, clculted yield grde, crcss weight nd nonconformnce (i.e. drk cutters). A crcss bse price of $105/cwt ws used for low Choice, yield grde 3 crcsses weighing 550 to 950 lb. Discounts were clculted s: $10, Select; $20, Stndrd; $30, drk cutters; $25, light (<550 lb) nd hevy (>950 lb) crcsses; nd $15, yield grdes 4 nd 5. Premiums were clculted s: $8, Prime; $3, upper 2/3 Choice; nd $3, yield grdes 1 nd 2. Results In both experiments, dt re presented with deds nd rilers removed from the nlysis. Feed intke nd hed dys were djusted one dy prior to the removl of the niml from the pen s either ded or riler. Experiment 1. Dry mtter intke ws similr mong tretments. Heifers implnted with Synovex Plus gined 3.8% fster (P =.01) nd were 3.9% more efficient (P =.01) thn those implnted with Finplix-H (Tble 1). Heifers implnted with Synovex Plus nd fed MGA hd higher (P <.05) dily gins compred both to heifers implnted with Synovex Plus fed no MGA nd heifers implnted with Finplix-H fed MGA. Crcss chrcteristics re presented in Tble 1. Heifers implnted with Synovex Plus s the terminl implnt hd lower (P =.07) clculted yield grdes nd incresed longissimus muscle re (P =.06) compred with those implnted with Finplix-H. Mrbling scores (P <.01) nd the percentge of crcsses grding U.S.D.A. low Choice (P <.01) were reduced nd the percentge of crcsses grding Select ws incresed (P <.01) when heifers not being fed MGA were implnted with Synovex Plus compred with the Finplix-H/MGA progrm. Feeding MGA with the use of Synovex Plus s the terminl implnt eliminted ny deleterious effects on (Continued on next pge) Pge Nebrsk Beef Report

66 crcss qulity s indicted by higher (P <.01) percentge of U.S.D.A. Prime crcsses, little chnge in the percentge of U.S.D.A. Choice crcsses, nd similr (P =.47) mrbling scores compred with the Finplix-H/MGA progrm. There ws no effect of tretment on the percentge of upper 2/3 Choice or Stndrd grding crcsses. There ws no influence of tretment on the incidence of drk cutting crcsses. Feeding MGA, either when heifers were implnted with Synovex Plus or Finplix-H, incresed 12th rib ft thickness (P <.01), clculted yield grde (P =.01), nd mrbling score (P <.01). The percentges of crcsses grding U.S.D.A. Prime (P =.02) nd low Choice (P <.01) incresed with feeding MGA. This experiment demonstrtes tht Synovex Plus cn be used effectively with MGA to increse performnce without compromising crcss qulity reltive to progrm using Finplix-H nd MGA. Experiment 2. Dry mtter intke ws similr between the implnt strtegies (Tble 2). Heifers implnted with Synovex Plus gined 4.1% (P =.02) fster compred with those implnted with Finplix-H. Feed conversion ws similr between implnt strtegies. Crcss chrcteristics re presented in Tble 2. Crcss weight of heifers implnted with Synovex Plus ws 10 lb hevier (P =.10) compred with those implnted with Finplix-H. Longissimus muscle re, 12th rib ft thickness, yield grde nd mrbling score were similr between heifers implnted with Synovex Plus or Finplix-H. Additionlly, the distribution of U.S.D.A. qulity grde ws similr between implnt tretments. Economic Anlysis for Experiment 1 nd 2. A summry of the economic nlysis is provided in Tble 3. In experiment 1, cost of gin ws improved (P =.01) with Synovex Plus compred with Finplix- H. On live bsis, net profit(loss) ws incresed (P =.03) $14.00 or $9.01 Tble 2. Effect of implnt strtegy on performnce nd crcss chrcteristics in finishing heifers (Experiment 2). Implnt Strtegy SynPlus FinH Item MGA MGA SEM b P-vlue c Number of pens 3 3 Number of heifers Dys on feed Initil weight, lb Finl weight, lb d Dry mtter intke, lb Dily gin, lb Feed/gin Crcss weight, lb th rib ft, in Longissimus muscle re, sq. in Clculted yield grde Mrbling score e Qulity grde distribution f, % Prime Upper 2/3 Choice Low Choice Select Stndrd SynPlus MGA = Synovex Plus fed MGA; FinH MGA = Finplix-H fed MGA. b SEM = Stndrd error of the men. c T-test of significnce between implnt tretments. d Finl weight clculted s hot crcss weight divided by.63 (common dressing percentge). e Mrbling score: 4.0 = Slight; 4.5 = Slight 50; 5.0 = Smll; 5.5 Smll 50; etc. f Chi squre sttistics: Prime (P =.80); upper 2/3 Choice (P =.88); low Choice (P =.88); Select (P =.94); Stndrd (P =.19). Tble 3. Feeding economics of heifers implnted with Synovex Plus, with or without MGA supplementtion, or Finplix-H nd MGA. Implnt Strtegy SynPlus SynPlus FinH Item No MGA MGA MGA SEM b P-vlue c Experiment 1 Rtion cost d, $/ton Cost of feed, $/hed Non-feed cost e, $/hed Totl feeding cost, $/hed Cost of gin f, $/cwt g g h.35 Crcss vlue fij, $/cwt k l m.28 Profit(loss) n, $/hed Live bsis f gh g h 3.7 Crcss merit bsis k l k 3.8 Experiment 2 Rtion cost, $/ton Cost of feed, $/hed Non-feed cost e, $/hed Totl feeding cost, $/hed Cost of gin, $/cwt Crcss vlue j, $/cwt Profit(loss) n, $/hed Live bsis Crcss merit bsis SynPlus No MGA = Synovex Plus fed no MGA; SynPlus MGA = Synovex Plus fed MGA; FinH MGA = Finplix-H fed MGA. b SEM = Stndrd error of the men. c T-test of significnce between implnt tretments. d Includes feed mrk-up. e Averge of ll medicine, processing, nd other costs for ll replictions in experiment nd pproprite implnt costs per tretment. f Contrsts of Synovex Plus tretments versus Finplix-H differ (P <.05). g,h Mens within row with different superscripts differ (P <.05). i Contrsts of MGA tretments versus no MGA differ (P <.05). j Clculted using $105/cwt crcss bse price: discounts = $10, Select; $20, Stndrd; $15, yield grde 4 nd 5; $30, drk cutter; premiums = $8, Prime; $3, upper 2/3 Choice; $3, yield grdes 1 nd 2. k,l,m Mens within row with different superscripts differ (P <.10). n Initil niml cost = $70/cwt; niml returns bsed on $65/cwt live csh price or clculted crcss vlue, respectively, interest not included Nebrsk Beef Report Pge 66

67 when heifers were implnted with Synovex Plus with or without MGA supplementtion, respectively, compred to Finplix-H with MGA supplementtion. When crcss discounts nd premiums were pplied to clculte profit(loss), heifers implnted with Synovex Plus without MGA supplementtion were similr to those implnted with Finplix-H nd fed MGA. The reductions in percentge of cttle grding low Choice in this experiment were lrge enough, using $10 Choice/ Select spred, to offset the dvntge in cost of gin. Although not sttisticlly different, the incidence of drk cutting crcsses ws included in this clcultion t discount of $30/cwt. The dditive effect of implnting heifers with Synovex Plus nd feeding MGA incresed crcss merit returns (P <.09) by $10.95 per hed compred to the Finplix-H, MGA fed heifers. In experiment 2, cost of gin ws not significntly influenced by implnt tretment. Overll profit(loss) tended (live bsis, P =.23; crcss bsis, P =.19) to be greter for heifers implnted with Synovex Plus. These dt suggest tht Synovex Plus cn be used in feedlot heifers to enhnce dily gin nd improve net live bsis profit(loss) compred with implnt progrm using Finplix-H. Crcss qulity is similr between heifers implnted with Synovex Plus or Finplix-H when MGA is included in the diet, incresing overll net crcss merit profit(loss) in Synovex Plus heifers. 1 Csey Mcken, grdute student; Todd Milton, ssistnt professor, Animl Science, Lincoln; Bill Dicke, Cttlemen s Consulting, Lincoln; Dve McClelln, McClelln Consulting, Fremont; Frnk Prouty, Fort Dodge Animl Helth, Overlnd Prk, KS. The Effect of Feeding Pressed Sugr Beet Pulp in Beef Cttle Feedlot Finishing Diets Jessic Prk Ivn Rush Todd Milton Burt Weichenthl 1 Feeding pressed beet pulp in plce of corn silge in finishing diet resulted in equl feed efficiencies though dry mtter intke ws slightly ffected. Summry Two trils were conducted to evlute feeding pressed beet pulp s the roughge source in finishing diets. British crossbred steers were fed 8.5% corn silge, 8.5% beet pulp, or 12.5% beet pulp with the reminder of the diet consisting of dry rolled corn nd supplement. When the two trils were nlyzed together, verge dily gin ws higher in the corn silge tretment compred to the two levels of beet pulp. However, feed to gin conversions between the tretments were not different. Beet pulp cn serve s substitute for corn silge nd even though dry mtter intke my be slightly ffected, feed efficiency will be equl. Introduction Sugr beet pulp is byproduct of the sugr beet industry. After the sugr is extrcted from the beet, the remining frction is mechniclly pressed to round 24% dry mtter. The pulp cn be fed fresh or ensiled, llowing it to be ccessible yer round. Previous studies hve shown tht replcing corn silge dry mtter with incresing levels of beet pulp hve improved verge dily gin nd feed efficiency in growing beef cttle diets (1992 Nebrsk Beef Report, pp , 1993 Nebrsk Beef Report, pp , 2000 Nebrsk Beef Report, pp ). Replcing ll of the corn silge in the diet (10 % diet dry mtter) with beet pulp resulted in similr dily gins nd trend towrd improved feed efficiency in feedlot finishing diet (1993 Nebrsk Beef Report, pp ). The NDF nd ADF of beet pulp (54% nd 33%, respectively) re similr to those of corn silge (51% nd 28%, respectively). Beet pulp hs highly digestible fiber frction, nd is therefore considered to be both n energy nd roughge source in beef cttle diets. Becuse of similr energy vlues, the costs re usully comprble on dry mtter bsis. However, little is known how or if beet pulp functions s roughge source in the diet. Therefore, the objective of this experiment ws to determine if beet pulp could replce corn silge (DM bsis) s fiber source in feedlot finishing diet. Procedure Two groups of British crossbred yerling steers were used in seprte trils in complete rndomized design. In Tril 1, 118 steers (initil BW 1030 lb) were ssigned rndomly to one of 12 pens with nine or 10 steers per pen. Pens then were ssigned rndomly to one of three dietry tretments, with four replictes per tretment. All steers were fed for 77 dys. In Tril 2, 90 steers (initil BW 859 lb) were ssigned rndomly to one of nine pens with 10 steers per pen. Pens were then rndomly ssigned to dietry tretment s in Tril 1. There were 3 replictes per tretment nd steers were fed for 133 dys. In both trils, steers were individully weighed for two consecutive dys t the initition of the tril nd every 28 dys throughout the feeding period. The three diet tretments (Tble 1) on DM bsis were: 8.5% corn silge (CON), 8.5% beet pulp (8.5BP), nd 12.5% beet (Continued on next pge) Pge Nebrsk Beef Report

68 pulp (12.5BP). The 8.5% beet pulp tretment replced the 8.5% corn silge on one to one bsis. The 12.5% beet pulp tretment hd the sme level of NDF s tht supplied by the 8.5% corn silge tretment. The reminder of the diets consisted of dry rolled corn nd protein supplement. The diets were formulted to be isonitrogenous t 13% CP. In Tril 1, the beet pulp ws stored on concrete pd for severl months prior to the tril, while it ws fed fresh in Tril 2. Steers were implnted with Revlor S t the beginning of the finishing period. Crcss chrcteristics were tken t the time of slughter. Finl weights, used to clculte ADG nd feed to gin, were clculted from hot crcss weight (HCW) djusted to common dressing percentge (62%). Performnce dt were nlyzed using the GLM procedures of SAS with feedlot pen s the experimentl unit. Qulity grdes were nlyzed using the chi-squre procedure of SAS. Significnce ws determined t P =.10 unless otherwise specified. Results Steer performnce is shown in Tble 2. Dt were tested for tretment by tril interctions. There ws no tretment by tril interction for ADG (P =.18). Gins were higher in the CON tretment compred to the 8.5BP nd 12.5BP tretments (P =.05). A significnt tril by tretment interction (P =.08) occurred for DMI, therefore dry mtter intkes re reported within tril. In Tril 1, cttle consuming CON hd higher DMI (26.2 vs nd 23.6, for CON, 8.5BP,nd 12.5BP, respectively; P <.001) thn steers fed the pulp rtions, but no differences in DMI between the 8.5BP nd the 12.5BP tretments occurred. In Tril 2, no differences in DMI cross the tretments were indicted. The different responses observed for DMI s beet pulp replced corn silge in the diet my hve been due to the storge of the beet pulp. In Tril 1, the beet pulp ws ensiled for severl months prior to feeding nd in Tril 2 the pulp ws fed fresh. There ws not significnt tretment by tril interction ( P =.96) in feed conversion. Therefore, dt were pooled nd no differences in Tble 1. Diet dry mtter composition nd clculted nutrient nlysis. Tretment CON 8.5BP 12.5BP Diet composition, dry mtter bsis, % Corn silge Beet pulp Dry rolled corn Protein supplement 58 b Protein supplement 40 c Clculted nutrient composition, dry mtter bsis Dry mtter, % Crude protein, % NEm, Mcl/cwt NEg, Mcl/cwt Rumensin, g/ton CON = Dry-rolled corn control with 8.5% corn silge; 8.5BP = 8.5% bet pulp replcing corn silge; 12.5BP = 12.5% beet pulp replcing corn silge nd dry rolled corn. b Supplement contins 58 percent crude protein, with Rumensin t 420g/ton, ir dry bsis. c Supplement contins 40 percent crude protein, ir dry bsis. Tble 2. Performnce of steers in tril 1 nd tril 2 fed dry-rolled corn bsed finishing diets with corn silge or wet beet pulp s the roughge source. Tretment CON 8.5BP 12.5BP DMI, lb/dy b Tril c 23.4 d 23.6 d Tril ADG, lb/dy 3.44 c 3.18 d 3.19 d Feed/gin CON = dry-rolled corn control with 8.5% corn silge; 8.5BP = 8.5% beet pulp replcing corn silge; 12.5BP = 12.5% beet pulp replcing corn silge nd dry-rolled corn. b Significnt tretment x tril interction (P =.08). c,d Mens within the sme row bering different superscripts differ (P <.05). Tble 3. Crcss chrcteristics of steers fed dry-rolled corn bsed finishing diets with corn silge or wet beet pulp s the roughge source. Tretment CON 8.5BP 12.5BP Tril 1 nd Tril 2 Hot crcss weight, lb 812 b 796 c 799 c Bckft, in.39 d.38 e.38 e Ribeye re, in Mrbling score f 5.27 d 4.84 e 5.11 de Yield grde g U.S.D.A. Choice or bove, % h CON = dry-rolled corn control with 8.5% corn silge; 8.5BP = 8.5% beet pulp replcing corn silge; 12.5BP = 12.5% beet pulp replcing corn silge nd dry-rolled corn. b,c Mens on sme row with different superscripts re different (P <.10). d,e Mens on sme row with different superscripts re different (P <.05). f Slight 0 = 4.0, Slight 50 = 4.5, Smll 0 = 5.0, Smll 50 = 5.5, etc. g Yield grde = (2.5 * bckft) + (.0038 * hot crcss weight) + (.2 * kidney-pelvic-hert ft) - (.32 * ribeye re). h Chi-squre sttistic (P =.09). feed conversion between the three tretments were detected. Beet pulp cn effectively replce corn silge in finishing diet nd it ppers tht the feeding vlue is similr (DM bsis). Crcss dt re shown in Tble 3. There were no tretment by tril interctions (P >.10) for crcss chrcteristics, therefore dt were pooled. Hot crcss weights were higher for the CON tretment (P <.10). The CON tretment hd higher mrbling scores compred to 8.5BP (P <.05), but it ws not different from 12.5BP. Bckft ws higher in the 2001 Nebrsk Beef Report Pge 68

69 CON tretment compred to the two levels of beet pulp (P <.05). No differences between tretments for ribeye re or yield grde were found. Qulity grdes were nlyzed by chi-squre distribution. The percent grding Choice or bove vried by tretment (P =.09). Feed conversions between the corn silge nd beet pulp diets were similr. There ws difference in DMI between the CON nd beet pulp tretments, lthough when the two levels of beet pulp were compred, they were not different. Beet pulp cn serve s replcement for corn silge in finishing diets nd it hs similr feeding vlue. In this experiment, dry mtter intke ws slightly ffected, however feed efficiency ws not different when beet pulp ws fed. These results gree with those reported in the 1993 Nebrsk Beef Report (pp ) where dily gins nd feed conversions were not different when 10% corn silge ws replced with 10% beet pulp on DM bsis in finishing diet. 1 Jessic Prk, grdute student; Ivn Rush nd Burt Weichenthl, professors, Animl Science, Pnhndle Reserch nd Extension Center, Scottsbluff; Todd Milton, ssistnt professor, Animl Science, Lincoln. Effects of Feeding Regimen on Performnce, Behvior nd Body Temperture of Feedlot Steers Shne Dvis Terry Mder Simone Holt Wnd Cerkoney 1 Chnging feeding regimen of feedlot nimls during potentil het stress periods cn effectively lower body temperture, thus decresing the risk of possible het relted production losses. Summry One hundred forty-four predominntly Angus x Chrolis steers were used to determine effects of different feeding regimens on performnce, behvior nd tympnic tempertures of steers under environmentl het stress. Steers were ssigned to one of three tretments: 1) d libitum fed t 0800 hr (ADLIB); 2) fed t 1600 hr with bunks slick by 0800 hr (BKMGT); nd 3) fed 85% of predicted DMI t 1600 hr (LIMFD). Tretments were imposed for 23 dys fter which ll steers were llowed d libitum ccess to feed t 0800 hr. Overll performnce ws not ffected by tretment. Altering feed time nd mount reduced tympnic temperture nd ltered eting pttern. Introduction Dily feed intke contributes to the metbolic het lod of nimls. When nimls re presented with dverse climtic conditions consisting of elevted mbient temperture, reltive humidity, nd solr rdition, they my be unble to effectively dissipte metbolic het lod. Altering feeding regimen during times of potentil het stress my be beneficil in mintining overll performnce. Possible strtegies for ltering the timing or reducing the pek metbolic het lod include djusting the time of feed consumption nd limit-feeding, respectively. Reserch hs shown limit-feeding my reduce metbolic rte nd improve overll efficiency when cttle re subsequently provided d libitum ccess to feed. The objectives of our study were to determine effects of ltered feeding regimen on performnce nd chnges in eting behvior of feedlot steers during potentil het stress periods. Additionlly, tympnic tempertures of the steers were monitored under both thermoneutrl nd hot environmentl conditions to determine ltertions in body temperture in response to ltered feeding regimen. Procedure One-hundred forty-four Angus x Chrolis steers were used. Upon initition of the tril steers were implnted with Synovex-Plus with verge body weight on two consecutive dys serving s initil weight. Steers were blocked by color (blck or white) nd rndomly ssigned to one of 24 pens. All steers were fed 65 Mcl/cwt NEg rtion consisting of (DM bsis): 84% dry rolled corn, 7.5% lflf hy, 4.5% liquid supplement, 2% soyben mel nd 2% dry supplement. Tretments were ssigned to pens nd consisted of: 1) d libitum feeding t 0800 hr (ADLIB); 2) bunk mngement, feed delivered t 1600 h nd mnged to be empty by 0800 hr (BKMGT); nd 3) limit-fed, delivered 85% of predicted DMI t 1600 hr (LIMFD). Tretments were initited on dy 0 (June 23, 1999) nd imposed for 23 dys (mnged feeding phse), then ll nimls were llowed d libitum ccess to feed delivered t 0800 hr. Dily feed nd wter intkes were recorded. Body weights were obtined on dys 23 nd t the termintion of the tril (dy 82; Sept. 13, 1999). On dy 83 steers were trnsported to commercil slughter fcility. Hot crcss weight, ft thickness, mrbling score, nd yield (Continued on next pge) Pge Nebrsk Beef Report

70 grde were obtined. An utomted wether sttion, locted in the center of the fcility, compiled minute by minute monitoring of temperture (T), reltive humidity (RH), blck globe temperture (BGT), wind speed nd wind direction into hourly observtions. Temperture humidity nd blck globe-humidity indices (THI nd BGTHI, respectively) were clculted hourly using the wether sttion dt to chrcterize the climtic het lod experienced by the nimls. The THI eqution is defined s: THI = T (.55 (.55 * (RH/100))) * (T 58) The BGTHI is determined by substituting BGT for T in the eqution. Blck globe is more comprehensive in its evlution of wether conditions becuse it incorportes the effects of wind speed nd solr rdition long with temperture. Behviorl observtions were mde t 0900, 1300, 1700 nd 2100 hr on vrious dys throughout the tril nd included ssessments of pnting nd feed vilble in the bunk. Pnting scores were ssigned to ech niml nd consisted of the following: 0 = norml brething; 1 = slightly elevted respirtion rte; nd 2 = excessive pnting ccompnied by slivtion. Bunk scores were ssigned on pen bsis nd consisted of the following: 0 < 10% of the dys feed mount left in bunk; 1 = 10 50% of the dys feed remining; nd 2 > 50% of the dys feed remining in the bunk. Upon termintion of the tril, dt were grouped ccording to climtic conditions (thermoneutrl vs. hot) nd feeding phse (mnged vs. d libitum). This resulted in five distinct periods consisting of: 1) MTNL 1; thermoneutrl conditions (THI < 74) during the mnged feeding period, dys 9 nd 13; 2) MHOT 1; hot environmentl conditions (THI > 75) during the mnged feeding period, dys 11 nd 12; 3) MTNL 2; thermoneutrl conditions (THI < 74) during the mnged feeding period, dys 14 nd 15; 4) MHOT 2; second episode of hot environmentl conditions (THI > 75) during the mnged feeding period, dys 21 nd 22; nd 5) AHOT; hot environmentl conditions (THI > 75) during the Tble 1. Effect of feeding regimen on feedlot performnce of yerling steers. Tretments Item ADLIB BKMGT LIMFD SEM b Body weight, lb Dy Dy d d e 5.7 Dy 82 d Dily gin, lb/dy Dys d 4.60 d 3.54 e.22 Dys d 2.88 d 3.63 e.11 Dys Dry mtter intke, lb/dy Dys d d e.29 Dys d ed e.48 Dys Feed:gin Dys Dys ed 8.43 d 7.35 e.26 Dys Wter intke, gl/dy Dys Dys Dys ADLIB = cttle were llowed ccess to feed t ll times; BKMGT = cttle were fed t 1600 hr with bunks slick t 0800 hr the following dy; LIMFD = cttle were fed 85% of their predicted dry mtter intke t 1600 hr b Stndrd error of men c Dy 82 body weight x.96 de Vlues within row with different superscripts differ (P <.05) d libitum period (dys 35 nd 36) Tympnic temperture (TT), n indictor of body temperture, ws determined using 24 nimls on dys 9-22 (mnged feeding) nd (d libitum). The sme nimls were used during ech period. Within ech pen, loggers were plced in one white nd one blck niml in order to determine if cot color contributes to het stress. Tempertures were collected hourly vi thermistor leds plced in the er cnl t n pproximte depth of 6". At this depth the led ws very ner the tympnic membrne of the steers. Thermistor leds were ttched to Stowwy XTI dt loggers which were secured in the er using pdded guze. Dt were grouped into three-dy periods, which overlpped the two-dy MHOT 1, MTNL 2, MHOT 2 nd AHOT behviorl periods. Performnce nd crcss dt were nlyzed using GLM procedures of SAS with tretment (TRT) nd repliction included in the model while behviorl ssessments were nlyzed by Chi-squre nlysis. Tympnic tempertures were nlyzed using repeted mesures ANOVA within TRT, niml, cot color nd niml(trt) in the model. Results Performnce of the steers during the tril is presented in Tble 1. Limit-fed steers hd lower (P <.05) BW, DMI, nd ADG thn BKMGT nd ADLIB steers during the mnged feeding period (dys 0-23). Following d libitum feeding of ll cttle, LIMFD steers compensted for their reduced growth during the mnged feeding period with 26.0 nd 23.1% higher (P <.05) ADG thn both ADLIB nd BKMGT steers, respectively, nd 7.5% higher (P <.05) DMI thn ADLIB steers. Limit-fed cttle were 14.7% more efficient following d libitum feeding thn BKMGT steers nd tended (P <.10) to be more efficient thn ADLIB. Results such s these re common in progrmmed gin nd limitfeeding studies. When overll performnce is compred, TRT differences were not significnt, suggesting ltering feeding regimen for 23 dys erly in the finishing phse does not impct performnce. It is noteworthy tht LIMFD cttle tended (P <.10) to consume less wter following the mnged feeding period thn ADLIB nd BKMGT steers. The reduction lso tended (P <.10) to influence overll wter intke in the sme 2001 Nebrsk Beef Report Pge 70

71 Men bunk score Figure 1. Effect of d libitum on bunkscores during vrying environmentl conditions. MTNL 1 = Thermoneutrl conditions (dys 9 nd 13); MHOT 1 = Hot environmentl conditions (dys 11-12); MTNL = Thermoneutrl conditions (dys 14-15); nd MHOT 2 = Hot environmentl conditions (dys 21-22). *Bunk scores differ (Chi-squre P-vlue <.05). Men bunk score * * Time of dy, h Time of dy, h 2100* MHOT 2 MTNL 2 MHOT 1 MTNL 1 Figure 2. Effect of bunk mngement feeding on bunkscores during vrying environmentl conditions. MTNL 1 = Thermoneutrl conditions (dys 9 nd 13); MHOT 1 = Hot environmentl conditions (dys 11-12); MTNL 2 = Thermoneutrl conditions (dys 14-15); nd MHOT 2 = Hot environmentl conditions (dys 21-22) Period MHOT 2 MTNL 2 MHOT 1 MTNL Period mnner. Crcss chrcteristics did not differ mong TRT (dt not shown). Pnting scores during TNL periods (MTNL 1 nd 2) were not ffected by TRT (dt not shown). Pnting scores were ffected by TRT (P <.10) in MHOT 1 (dt not shown). At 0900 hr, BKMGT steers hd the highest (P <.10) pnting score with LIMFD steers being intermedite (.10,.29, nd.21 for ADLIB, BKMGT, nd LIMFD, respectively). By 1300 hr no differences in pnting scores mong TRT were observed. However, by 1700 hr BKMGT nd ADLIB steers hd higher (P <.10) pnting scores thn LIMFD (.85,.88, nd.71 for ADLIB, BKMGT, nd LIMFD, respectively). The lower pnting scores of LIMFD steers likely re result of reduced metbolic het production due to their reduced intke. During the MHOT 2 period, similr trend in pnting scores to MHOT 1 ws observed. Eting behvior of steers on different feeding regimens ws chrcterized with bunk scores being grouped by tretment nd nlyzed cross environmentl period. It is generlly ssumed tht cttle will et lrge mel fter being fed nd then continue to periodiclly consume smller mels for the reminder of the dy. Environmentl conditions lter the feeding ptterns of steers such tht on hot dys, steers will tend to not consume s much feed. At 0900 hr, ADLIB steers hd similr bunk scores during the MTNL 1 nd MHOT 1 periods (Figure 1). These cttle becme more ggressive eters during MTNL 2 s exemplified by their considerbly lower bunk scores t 0900 hr. However, when mbient temperture ws elevted second time (MHOT 2), the steers ltered their eting pttern such tht they consumed little or no feed t 0900 hr. This shift in intke pttern of these steers during this period resulted in higher bunk scores t 1700 nd 2100 hr. Scores for BKMGT steers re presented in Figure 2. By design, BKMGT steers hd no feed in their bunks t the time of the 0900 nd 1300 hr observtions. Unlike ADLIB steers, steers in this TRT showed no ltertion in feed intke pttern ssocited with environ- (Continued on next pge) Pge Nebrsk Beef Report

72 mentl period. Although bunk scores during MHOT 1 nd 2 were numericlly higher thn the TNL periods, differences were not significnt (P >.05). This consistent eting pttern suggests tht feeding t 1600 hr llowed cttle to mintin uniform eting pttern under vrying environmentl conditions. A consistent eting pttern is very importnt in preventing metbolic disorders sometimes ssocited with het stress. Similr to BKMGT steers, LIMFD steers hd no feed t the 0900 nd 1300 hr observtions (Figure 3). At 1700 hr there ws significnt (P <.05) chnge in bunk scores cross environmentl period. During MTNL 1, steers consumed good proportion of their feed within the first hour ( hr). However, their intke ws slowed somewht during this sme time period of MHOT 1. This is likely due to the fct tht these nimls hd lredy experienced the hottest prt of the dy nd were reluctnt to et lrge mel. This, however, ws not the cse in the MHOT 2 period. In this period, LIMFD steers te ll of their feed within one-hour period. This ggressive eting behvior occurred despite elevted T ssocited with this period, possibly due to reduction in the metbolic rte nd het lod. Decreses in metbolic rte hve routinely been shown in nimls experiencing nutritionl restriction. Men tympnic tempertures of the steers during mnged nd d libitum feeding periods re presented in Tble 2. There were no TRT effects during MHOT 1. Cot color ws significnt during this time with blck-hired steers hving higher (P <.05) TT. By the MTNL 2 period, differences mong TRT were significnt (P <.05). During this period, BKMGT cttle hd lower (P <.05) TT thn both ADLIB nd LIMFD steers. The lck of TRT by hour interction (P >.10) suggests tht time of pek het lod ws not ltered by vrying feeding time. However, the mgnitude of the pek ws lower in BKMGT cttle possibly due to the fct tht pek metbolic het lod did not coincide with pek environmentl temperture. During MTNL 2 cot color by time interction (P <.05) ws observed with white-hired steers Men bunk score * Time of dy, h Figure 3. Effect of limit feeding on bunkscores during vrying environmentl conditions. MTNL 1 = Thermoneutrl conditions (dys 9 nd 13); MHOT 1 = Hot environmentl conditions (dys 11-12); MTNL 2 = Thermoneutrl conditions (dys 14-15); nd MHOT 2 = Hot environmentl conditions (dys 21-22). *Bunk scores differ (Chi-squre P-vlue <.05). 2100* MHOT 2 MTNL 2 MHOT 1 MTNL Tble 2. Min effect mens of tympnic temperture for feeding regime (top tble) nd cot color (bottom tble) of yerling feedlot steers under vrying environmentl conditions. Tretments Period ADLIB BKMGT LIMFD SEMc MHOT <.1 MTNL d e d <.1 MHOT d e f.1 AHOT g d e f.1 Cot color Period Blck White SEM c MHOT d e <.1 MTNL 2 g <.1 MHOT d e <.1 AHOT d e.1 MHOT 1 = Hot environmentl conditions (temperture-humidity index; THI > 74) during mnged feeding (dys 0 23), MTNL 2 = thermoneutrl conditions (THI < 74) during mnged feeding, MHOT 2 = second episode of hot environmentl conditions during mnged feeding, AHOT = hot environmentl conditions during d libitum feeding (dys 23 82). b ADLIB = d libitum feeding t 0800 h, BKMGT = fed t 1600 h with bunks slick by 0800 the following dy, LIMFD = fed 85% of predicted dry mtter intke t 1600 h. c Stndrd error of the men def Mens within row differ (P <.05) g Min effect interction with time (P <.05) Period hving lower TT t 1800 (104.4 vs , o F) nd 1900 (104.5 vs , o F) hr. The timing of these differences corresponds to the two to three hour lg typiclly ssocited with body temperture in reltion to T. The higher TT for blck-hired steers thn for whitehired steers is n indiction of the effects solr rdition hs on TT. Under pek climtic het lod, mximum TT differences between white nd blck cot colored steers rnged from.2 to.8 o F. Differences in TT due to hir color my be confounded with breed of the 2001 Nebrsk Beef Report Pge 72

73 Temperture, o F b b c b c b c b c c c c c c c c c c c b c b c b c b b b b b b b b ADLIB BKMGT LIMFD b b b b Time of dy, h Figure 4. Effect of feeding regimen on tympnic temperture of yerling feedlot cttle during hot (temperture-humidity index > 74) environmentl conditions during d libitum feeding (dys 36-38). bc Vlues within time differ (P <.05). nimls. However, there is no evidence to suggest tht TT of Bos turus steers is ffected solely by breed. Furthermore, the group ws of similr genetic composition. The lowered TT of LIMFD steers during the MHOT 2 period ws likely due to decresed metbolic rte tht often ccompnies prolonged feed restriction. The lck of TRT differences in these nimls erlier in the feeding period (MHOT 1; dys nd MTNL 2; dys 13-15) suggests decresed TT in response to limit-feeding is not instntneous. Although, cot color ffected TT during the MHOT 2 period with blck-hired steers hving higher (P <.05) TT thn white-hired steers. When ll steers were plced on d libitum feeding t 0800 hr, crryover effects of TRT were evident. A TRT by time interction ws noted for TT during the AHOT period (dys 34-36; Figure 4). Limit-fed steers hd lower (P <.05) TT thn ADLIB steers t ll times mesured with BKMGT cttle being intermedite. Bunk mngement steers were lower thn ADLIB steers from hr. The reduced TT of LIMFD steers following d libitum feeding is n importnt finding nd suggest benefits of limit-feeding cttle during period of potentil het stress re not restricted to only the time in which the cttle re limit-fed. Reductions in the TT of BKMGT reltive to ADLIB steers my prtilly be ttributed to lower DMI during the dys which TT were recorded (18.14, 17.45, lb/dy for ADLIB, BKMGT, nd LIMFD, respectively). Altering the feeding regimen of feedlot steers during the summer is mngement strtegy vilble to producers to mitigte dverse effects high summer tempertures hve on performnce. These chnges my lter tympnic temperture nd eting pttern without compromising overll performnce. If limit-feeding is chosen s mens to reduce overll het lod of feedlot steers, it should be initited for t lest two weeks before potentilly hot wether nd, bsed on these results, my by stopped pproximtely two weeks prior to the lst thret of het stress. Bunk mngement strtegies, such s the one employed in this study, pper to hve more immedite effects on reducing body temperture. 1 Shne Dvis, grdute student, Animl Science; Terry Mder, professor, Animl Science; Simone Holt, grdute student, University of Queenslnd-Gtton; Wnd Cerkoney, reserch technicin Pge Nebrsk Beef Report

74 Restricted Feeding Strtegies for Reducing Het Lod of Yerling Steers Terry Mder Simone Holt Tony Scott Shne Dvis 1 Restricting intke in feedlot cttle lowered body temperture during the summer. Summry Eighty-four Bos turus crossbred steers were used to investigte effects of level nd durtion of limit feeding feedlot cttle in hot environment. Restricting feed intke to 70 to 80% of d libitum for 21 dys durtion (RES21) or for 42 dys durtion (RES42) reduced tympnic temperture in both RES21 nd RES42 when compred with d libitum tretment groups under both thermoneutrl nd hot conditions. Temperture reduction pproched 1.5 F 0 depending on time of dy. Limit feeding feedlot cttle during erly summer is successful tool for enhncing niml comfort by lleviting the combined effects of high tempertures nd reltive humidities. Introduction Estimted economic losses to het stress in Nebrsk lone exceeded $20 million in 1999 due to reduced performnce nd cttle deth. A mjor source of economic loss to het stress is the reduction in feed intke, though the response is vrible nd dependent on the niml s therml susceptibility, cclimtion nd diet. However, mnged or controlled reduction in feed intke to lessen het stress my not cuse n economic loss. In some situtions feed restriction increses feed efficiency in ruminnts, possibly by lowering mintennce energy expenditure nd incresing diet digestibility. A further effect of feed restriction is possible chnge in diurnl rnge of internl body temperture. Our study ws undertken to investigte effects of level nd durtion of restricted feeding of feedlot cttle in hot environment on growth, feed efficiency nd metbolic response. In ddition, d libitum feeding of highenergy, high fiber diet, contining corn gluten feed (CGF), ws compred to d libitum feeding of trditionl dry rolled corn (DRC) bsed diet during the summer. Procedure As prt of previously reported study (2000 Nebrsk Beef Report, pp 41-43), 84 Bos turus crossbred steers were used in 63-dy study, beginning June 24, 1998, to ssess body temperture nd behvior pttern of feedlot cttle. Steers were blocked by weight. Within Tble 1. Composition (DM bsis) of corn gluten feed (CGF) nd dry rolled corn (DRC) bsed diets. Item CGF DRC Ingredient, % Corn silge 8 10 CGF 40 0 DRC Soyben mel Liquid supplement Dry supplement 3 2 Chemicl Crude protein, % NDF, % Dry mtter, % NEm Mcl/cwt NEg, Mcl/cwt block, steers of similr color were rndomly ssigned to ech pen to ensure similr number of red, white nd blck coted cttle were eqully distributed within ech pen. Pens of steers were then rndomly ssigned to tretments. Tretments were: 1) CGF-bsed rtion restricted to 70 to 80% of d libitum for 21 dys durtion (RES21), 2) CGF-bsed rtion restricted to 70 to 80% of d libitum for 42 dys durtion (RES42), 3) CGF-bsed rtion fed d libitum (CGFAD), nd 4) DRC-bsed rtion fed d libitum (DRCAD). Cttle on RES21 nd RES42 tretment groups were stepped up over four to six dys to d libitum following the 21- nd 42-dy restriction. Dily dry mtter intke of steers on CGFAD nd DRCAD ws projected using computer softwre (NRC, 1996), bsed upon breed type, ge, body 2001 Nebrsk Beef Report Pge 74

75 Tble 2. Dry mtter intke, lb/dy for ech period nd over the entire study. Tretment RES21 RES42 CGFAD DRCAD Period 1 (dy 1-21) 18.6 b 18.5 b 24.5 d 20.6 c Period 2 (dy 22-42) 23.8 c 18.7 b 24.9 d 26.1 e Period 3 (dy 43-63) 26.0 c 24.7 b 26.7 c,d 27.2 d Overll (dy 1-63) 22.8 c 20.7 b 25.4 d 24.7 d RES21 & RES42 = restricted fed corn gluten feed bsed diet (CGF) for 21 nd 42 dys, respectively. CGFAD & DRCAD = d libitum fed CGF nd dry rolled corn bsed diet (DRC), respectively. b,c,d,e Mens within row with different superscripts re different (P <.05). Tble 3. Men tympnic temperture (TT) of feedlot cttle fed under hot climtic conditions Tretment RES21 RES42 CGFAD DRCAD Dy c c d d Dy d c d e Dy d e d c Overll (dy 1-63) c c d d Climtic conditions where men dily THI ws equl to or greter thn 74. b RES21 nd RES42 = restricted fed corn gluten feed bsed diet (CGF) for 21 nd 42 dys, respectively. CGFAD nd DRCAD = d libitum fed CGF nd dry rolled corn bsed diet (DRC), respectively. c,d,e Mens within row with different superscripts re different (P <.05). condition nd frme size. The DMI of RES21 nd RES42 were djusted ccordingly from the projected mount. Diets (Tble 1) were formulted to contin minimum of 13.5% CP,.63% C,.35% P, nd.65% K, nd contined 25g/ ton Rumensin nd 10 g/ton Tyln (DM bsis). Steers were implnted with Revlor-S t the beginning of the tril. All steers were fed in the morning t pproximtely Steers were weighed t pproximtely 0800 on two consecutive dys (d -1 nd 0), prior to the strt of the tril, to obtin n verge strting weight. Steers were then weighed on dys 21, 42, nd 63. Temperture (T o F), reltive humidity (RH, %), nd other climtic dt were collected hourly throughout the study vi wether sttion locted t the feedlot fcilities. The primry indictor of het lod ws temperture-humidity index (THI); THI=T - ( (RH/ 100)) x (T 58). During ech of the three 21-dy periods, thermistors were inserted into n er cnl of totl of 12 steers (two/ d libitum groups nd four/limit-fed groups) within ech tretment for pproximtely seven-dy period to obtin tympnic temperture (TT) on n hourly bsis. Steers were selected bsed on cot color nd weight in n ttempt to compre similr steers mong tretments. Thermistor leds were plced into the er cnl, close to the tympnic membrne, to n pproximte depth of five inches. Dt loggers (Onset Dt Loggers, Pocsstt, MA.) were then connected to the thermistor, wrpped with pdded guze, plced on the inside of the er nd secured to the er. Within ech period, behvior dt (pnting nd bunching) were obtined during thermoneutrl (TNL) dys (THI less thn 74) nd hot (HOT) dys (THI equl to or greter thn 74) t Pnting score ws obtined by visul ssessment of flnk movements nd overll brething in individul steers. A score of 1 indicted little or no pnting nd 2 indicted moderte to excessive pnting with mouth opened nd/or slivtion occurring. At the sme time, bunching score ws ssigned. This mesure indictes the proximity of ech niml to its nerest neighbor (within pen), where 1 indictes nimls re bunched (ny prt of one niml within 3 feet of the midline of ny other niml, with midline determined from shoulders to tilhed) nd 2 indictes nimls re seprted from others. Results For the study s durtion, THI verged 71.5 nd rnged from dily verge of 64.2 to Men dily mbient temperture for the entire study ws 73.4 o F with n verge dily low nd high of 65.0 nd 83.4 o F, respectively, while reltive humidity rnged from 60% to 98% with men of 83.6%. By design, differences in DMI were found mong tretments (P <.05) during restricted feeding periods (Tble 2). These differences tended to be crried over into subsequent periods, in which cttle previously restricted in DMI lso hd significntly lower DMI during the period following restriction. Differences in tympnic temperture (TT) were found mong tretments within periods (P <.05; Tble 3). Restricting DMI reduced TT.6 to.8 o F when compred to d libitum fed cttle. On the verge, cttle fed d libitum diets (CGFAD vs DRCAD) hd equl TT, even though the CGFAD tretment group consumed slightly greter quntity of feed. The gretest environmentl chllenge ws experienced in period 2 (dy 22 to 42), in which both mximum mbient temperture nd mximum THI were obtined. During this period the cttle remining on the restricted DMI diet (RES42) hd the lowest overll TT. The gretest differences in TT, between this group nd the other tretment groups, begn to occur between 1600 nd 1700 hr. The TT in the RES42 group remined 1.0 to 2.0 o F below the TT of cttle in the other groups, throughout the nighttime hours (Figure 1). On the verge, TT of the other groups begn to decline pproximtely four hours lter thn TT of the RES42 cttle group. Within respective periods, no differences (P >.05) were found mong tretments for pnting or bunching score in either thermoneutrl (TNL) or hot (HOT) climtic conditions. However, within tretments, different proportions of cttle were bunched nd pnting (Tble 4). This is prticulrly evident in periods 2 nd 3, in which cttle ssigned to the CGFAD tretment hd the gretest percentge of cttle bunched nd greter percentge of cttle pnting. In generl, (Continued on next pge) Pge Nebrsk Beef Report

76 105.0 RES21 RES CGFAD DRCAD Tympnic Temperture (F) Hour Figure 1. Hourly tympnic temperture (TT) of cttle fed vrious diets from dy 21 to dy 42. Tble 4. Chi squre nlysis of percentge of cttle pnting nd bunching by tretment nd period. Pnting score (period 1) Pnting score (period 2) Pnting score (period 3) Item 1 2 P vlue 1 2 P vlue 1 2 P vlue RES21 Bunching score b RES42 Bunching score b CGFAD Bunching score b DRCAD Bunching score b Pnting score 1 = % of cttle showing little or no pnting, 2 = % of cttle showing moderte to excessive pnting. b Bunching score 1 = % of cttle bunched together, 2 = % of cttle not bunched. cttle tht re pnting tend to disply greter level of bunching. Bunching is often observed with cttle under het stress nd possibly contributes to dded het lod by diminishing ir flow. Cot color (blck or white) ws found to hve significnt (P <.01; Tble 5) effect on pnting score. When verged cross diet tretments, blck cttle hd the gretest percentge of cttle showing moderte to excessive pnting, while white cttle displyed the lest pnting under TNL climtic conditions. A similr pttern ws seen under HOT climtic conditions. The percentge of cttle showing moderte to excessive pnting increses pproximtely 30% from TNL to HOT conditions. Only when cttle were exposed to HOT climtic conditions did trends in bunching become pprent. Under HOT conditions, drk 2001 Nebrsk Beef Report Pge 76

77 Tble 5. Chi squre nlysis of percentge of cttle pnting nd bunching by climtic conditions nd cot color. Hide color Item Blck White P vlue Thermoneutrl conditions (THI < 74) Pnting score <.01 Bunching score b Hot conditions (THI 74) Pnting score <.01 Bunching score Pnting score 1 = % of cttle showing little or no pnting, 2 = % of cttle showing moderte to excessive pnting. b Bunching score 1 = % of cttle bunched together, 2 = % of cttle not bunched. (P <.03) to period 3 (P <.14). Thus, the percentge of white nimls bunching ppers to increse over time, s body condition nd dys of feed increse. These dt suggest tht s white cttle get ftter, they tend to behve more like the blck cttle under hot conditions. Under hot environmentl conditions, het lods cn be reduced by restricted feeding which is beneficil in protecting cttle from the effects of hot, humid conditions. However, the preferred length of time to limit-feed, prior to het episode, is still in question. Immedite benefits to restricting DMI occur by reducing metbolic het lod, however, dditionl benefits likely occur, longer term, in which metbolic rte nd ssocited het production re reduced. cttle bunched more (P <.08) thn white cttle. Since cttle of different cot colors were in the sme pens, it would pper tht the white cttle tend to sty wy from the drk cttle. Whether they re not bunching becuse they re cooler, hving fewer problem with flies thn blck cttle, or sense het coming from the blck nimls, is not known. Although not shown, observed effects of cot color on bunching tended to diminish over time, prticulrly from period 2 1 Terry Mder, professor, Animl Science, Hskell Ag. Lb., Concord; Simone Holt, grdute student, Deprtment of Animl Production, University of Queenslnd-Gtton, Gtton, Queenslnd, Austrli; Tony Scott, reserch technicin, Animl Science, Lincoln; Shne Dvis, grdute student, Animl Science, Lincoln. Mnging Het Stress in Feedlot Cttle Using Sprinklers Shne Dvis Terry Mder Wnd Cerkoney 1 Wter ppliction to feedlot mounds lowers body temperture of steers without dversely ffecting mound microclimte. Summry Ninety-six Bos turus steers were used to determine the effect of wter ppliction to feedlot mounds on performnce, behvior nd tympnic temperture of steers nd microclimtic conditions of the mounds. Steers were ssigned to 12 pens subjected to no wter ppliction (CON), wter pplied between 1000 nd 1200 (AM), or 1400 nd 1600 hr (PM). Wter ppliction lowered soil tempertures of the mounds with little effect on temperture-humidity index. Tympnic tempertures were lowered by tretment. Performnce vribles were not ffected; however, AM steers were more efficient thn PM steers. Introduction Reductions in performnce of feedlot cttle during summer months cn be in lrge prt due to elevted mbient ir temperture. These detrimentl effects my be further compounded when elevted mbient temperture is coupled with high humidity, low wind speed nd/ or solr rdition. When these dverse wether prmeters exist, the grdient by which het is trnsferred from the niml to the environment is reduced nd in extreme situtions my ctully be reversed so tht the niml is gining het. Mngement strtegies such s ltering metbolizble energy intke nd providing shde structures for the nimls to reduce het stress hve been explored nd re vible options to beef producers. Use of sprinklers to pply wter to the cttle nd mound in the pen is nother option. While sprinkling systems hve been extensively used nd reserched in diry, poultry nd swine opertions, few studies exist exmining their effect on feedlot nimls in the High Plins. Therefore, the objective of this study ws to determine the effects of wter ppliction to feedlot mounds (Continued on next pge) Pge Nebrsk Beef Report

78 during the summer on performnce nd behvior of feedlot steers. Chnges in tympnic tempertures of the nimls nd microclimtic conditions of the mounds during wter ppliction were exmined. Procedure Ninety-six Bos turus, (predominntly Angus nd Angus x Hereford) yerling steers were used for this study. Upon initition of the tril (June 23, 1999) steers were implnted with Synovex-Plus nd weighed with the verge body weight on two consecutive dys used s initil weight of the steers. Steers were llotted to one of 12 pens bsed on initil weight nd llowed d libitum ccess to 65 Mcl NEg/cwt finishing diet which contined (DM bsis): 84% dry rolled corn, 7.5% lflf hy, 2% soyben mel, 2% dry supplement, 4.5% liquid supplement. Four replictes were ssigned to ech of three tretments (TRT); 1) control; 2) wter pplied to mounds between hr (AM); nd 3) wter pplied to mounds between hr (PM). Wter ws pplied to the AM nd PM mounds using Rinbird Pop-Up Sprinklers when predicted men dily temperture-humidity index ws > 74. This resulted in wter being pplied on 23 dys of the 82-dy study. Wter flow ws controlled using mnul vlves nd wter flow meter so s to supply 9 gl/hd/dy. A semi-circulr re ws wetted to provide 26 ft 2 of wetted surfce per niml. Time of wter ppliction ws controlled using two-cycle utomtic vlve. Dily feed nd wter intkes were recorded. Body weights were obtined on dy 34 nd t the termintion of the tril (dy 82; Sept. 13, 1999). On dy 83 steers were trnsported to commercil slughter fcility. Hot crcss weight, ft thickness, mrbling score nd yield grde were obtined. An utomted wether sttion in the center of the fcility compiled minute by minute monitoring of temperture (T), reltive humidity (RH), blck globe temperture (BGT), wind speed nd wind direction into hourly observtions. Temperture humidity nd blck globehumidity indices (THI nd BGTHI, respectively) were clculted hourly nd verged dily using the wether sttion dt. The THI eqution is defined s: THI = T (.55 (.55 *(RH / 100)) * (T 58) The BGTHI is determined by substituting BGT for T in the eqution. Blck globe is more comprehensive in its evlution of wether conditions becuse it incorportes the effects of wind speed nd solr rdition long with temperture nd humidity. Climtic conditions of the mounds were recorded on dys 30 through 33 using HOBO Pro dt loggers. Loggers plced t heights of 6" nd 42" on fence posts bisecting the mounds lengthwise recorded T nd RH every fifteen minutes. For nlyticl purposes, redings t , , , , , nd hr were verged to provide six observtions per dy. Rdition shields were positioned round the loggers to prevent exposure to direct sunlight nd contct with wter during sprinkling. Wire cges were positioned round the shields to prevent niml tmpering. Soil tempertures of the mounds were mesured using loggers plced t height of 24 inches nd equipped with temperture probe. The probe ws inserted into the soil t depth of.5" to monitor soil temperture; dditionlly the logger collected T t 24 inches. After nlysis, there ws no difference between T t 24 inches nd 42 inches, thus the 24 inches T re not shown. Temperture humidity index ws clculted using mesurements of 6 nd 42 inches. Tympnic temperture (TT), n indictor of body temperture, ws determined on 2 nimls/rep/trt (8 nimls/ tretment) on dys 30 through 33. Tempertures were collected hourly vi thermistor leds plced in the er cnl t n pproximte depth of 6". At this depth the led ws very ner the tympnic membrne of the steers. Thermistor leds were ttched to dt loggers which were secured in the er. Behviorl observtions were mde t 0900, 1300, 1700, nd 2100 during three periods of hot environmentl conditions ccompnied by wter ppliction to mounds. These periods were clssified ccording to the time of the tril tht they occurred nd their men dily THI nd BGTHI. The periods were: 1) Erly Hot (dys 11 12; THI = 77, BGTHI = 81); 2) Lte Hot (dys 21 22; Tble 1. Effect of morning nd evening mound wetting on feedlot performnce of yerling steers. Tretments Contrst P-vlues b Item CON AM PM SEM c CON vs TRT AM vs PM Body weight, lb Dy Dy Dy 82 d Dry mtter intke, lb/dy Dy Dy Dy Averge dily gin, lb/dy Dy Dy Dy Feed:Gin Dy Dy Dy Wter intke, gl/dy Dy Dy Dy CON = control; AM = wter pplied to mounds between hr; PM = wter pplied to mounds between hr. b Single degree of freedom orthogonl contrsts of CON vs. men of AM nd PM, nd AM vs. PM. c Stndrd error of the men. d Dy 82 live weight multiplied by.96% Nebrsk Beef Report Pge 78

79 THI = 76, BGTHI = 80); 3) Very Hot (dys 30 31; THI = 78, BGTHI = 85). The Very Hot period coincided with the het wve tht ffected Nebrsk in July Behviorl observtions mde during these times included ssessments of pnting, pen position of the nimls, nd feed vilble in the bunk. Pnting scores were ssigned to ech niml nd consisted of the following: 0 = norml brething; 1 = slightly elevted respirtion rte; nd 2 = excessive pnting ccompnied by slivtion. Bunk scores were ssigned on pen bsis nd consisted of: 0 = < 10% of the dys feed mount left in bunk; 1 = 10 50% of the Temperture, o F dys feed remining; 2 = > 50% of the dys feed remining in the bunk. Performnce nd crcss dt were nlyzed using the GLM procedures of SAS (1986) with the model including the fixed effects of TRT nd replicte. Single degree of freedom orthogonl contrsts were used to determine differences mong tretments. The contrsts used were CON vs. AM nd PM nd AM vs. PM with P-vlue <.10 being considered significnt. Behvior dt ws nlyzed using Chi-squre test with men pnting nd bunk score determined for ech tretment. Tympnic tempertures nd climtic conditions of the CON AM PM Time of dy, h Figure 1. Effect of wter ppliction to feedlot mounds on soil temperture. bc Vlues within time differ (P <.05). Temperture, o F b c b b b b Time of dy, h Figure 2. Effect of wter ppliction to feedlot mounds on mbient ir temperture t height of 42 inches. b Vlues within time differ (P <.05). b c b b c b b c CON AM PM b b mounds were nlyzed using repeted mesures. Results Overll performnce during the tril ws not ffected by wter ppliction to the mounds (Tble 1). However, feed conversion ws improved (P <.10) for AM vs. PM from dy 34 until the termintion of the tril. This difference subsequently resulted in AM steers hving improved (P <.10) feed conversions over the entire feeding period. Wter intke ws ffected by TRT with AM steers consuming significntly more wter from dy 0 34 thn PM steers. Crcss chrcteristics were not ffected by TRT (dt not shown). Pnting scores did not differ t ny observtion during Erly Hot or Lte Hot environmentl periods (dt not shown). Pnting scores did not differ t 0900, 1300 or 2100 during the Very Hot period. However, t 1700, men pnting score for PM cttle ws lower thn CON with AM being intermedite. Scores were 1.92, 1.83, nd 1.59 for CON, AM nd PM, respectively. Bunk scores were not ffected by tretment during Erly, Lte or Very Hot environmentl periods. Although not significnt, there ws slight numeric trend for PM steers to hve slightly lower bunk scores t 1300, 1700 nd 2100, thus PM steers tended to consume more feed prior to these times during the Very Hot period. A TRT by position by time interction (P <.01) ws found for mound tempertures, thus dt were nlyzed within position nd time nd re shown in Figures 1 nd 2. Soil tempertures (Figure 1) of CON mounds were higher (P <.01) thn AM nd PM t ll times nd reched mximum of o F t Mounds wetted in the fternoon were cooler overnight thn AM mounds s evidenced by their lower (P <.05) tempertures t 0730 (75.6 vs o F). Tempertures of AM nd PM mounds were similr t 1000 (vg. = 79.3 o F) nd 0 hr (vg. = 86.2); however, PM mounds were lower thn AM t 1500, 1730, nd (Continued on next pge) Pge Nebrsk Beef Report

80 Tempertures t 6" (dt not shown) were similr cross TRT t 0730, 1000 nd 0 nd verged , , nd o F, respectively. At 1500, PM mounds were lower thn AM nd CON nd continued to be lower thn CON t 1730 nd Tempertures t 42 inches (Figure 2) followed similr trend with no TRT effect t 0730, 1000, nd 0, but PM mounds were gin lower thn AM nd CON t 1500 nd continued to be lower thn CON t 1730 nd 2000 with AM being intermedite. Reltive humidities bove the mounds (Figure 3) did not differ (P >.10) by position (height bove mound), therefore position dt were pooled. The TRT by time interction ws significnt (P <.01), thus mens within time were compred s previously described for temperture. As expected, wter ppliction incresed RH of the mounds. Tretment mounds hd similr RH except t 1500 when PM mounds were higher (P <.05; vs ). This increse in RH of the PM mounds is likely due to the time of mesurement coinciding with sprinkling time. Although TRT nd CON mounds were different t 2000, RH for ll mounds ws similr t 0730, suggesting tht RH ws similr during the overnight hours. Temperture-humidity indices of the mounds t the vrious time points re presented in Figure 4. Like RH, position t which the reding ws obtined ws not significnt, thus results were pooled for nlysis. The TRT by time interction ws significnt (P <.01), thus mens within time re seprted by lest significnt difference. The THI is derived from both mbient temperture nd humidity nd hs been suggested to be more indictive of the ctul het lods the niml is experiencing s opposed to temperture or humidity lone. Temperture-humidity indices only differed between tretments t the 1500 nd 1730 redings. At 1500, PM mounds, despite hving significntly higher RH, hd lower THI thn both CON nd AM mounds (85.0, 84.12, nd for CON, AM, nd PM respectively). At 1730, PM THI ws still lower thn CON with AM being intermedite (84.0, 83.2, nd 82.2 for CON, AM, nd PM, respectively). Tympnic tempertures (TT) of the Reltive humidity, % Temperture-humidity index Time of dy, h CON AM PM Time of dy, h Figure 4. Effect of wter ppliction to feedlot mounds on men temperture-humidity index. b Vlues within time with different superscripts differ (P <.05). b b b CON AM PM Figure 3. Effect of wter ppliction to feedlot mounds on men reltive humidity. b Vlues within time with different superscripts differ (P <.05). steers re presented in Figure 5. Tretment by time interction ws significnt (P <.001). Steers in the AM tretment hd lower (P <.05) TT thn CON nd PM cttle beginning t 2300 nd lsting through Nighttime cooling of cttle is essentil in the mintennce of homeothermy. Low TT my be indictive of mechnism by which the het cpcity of nimls is incresed, thus enbling them to tolerte higher dytime tempertures. Control nd PM cttle hd similr TT except t 1700, when PM hd b b b lower (P <.05) TT thn CON nd AM steers. Overll TT were 103.2, nd o F for CON, AM, nd PM steers, respectively. During the corresponding time period in which TT ws mesured, DMI for the TRT verged 16.83, nd for CON, AM, nd PM respectively. The lower DMI of the AM cttle my hve contributed to their lower TT. Appliction of wter to feedlot mounds is vible option to provide cool re in pen where cttle cn seek b b 2001 Nebrsk Beef Report Pge 80

81 Temperture, o F b b b 1400 b b 1600 b 1800 b b Time of dy, h b 2400 b b 0200 b b 0400 b 0600 CON AM PM b b b relief from het stress conditions. Although RH over the mound is incresed, the decrese in microclimte temperture ssocited with wter ppliction results in either no effect or concomitnt lowering of THI. The decrese in temperture is significnt in llowing for mximiztion of the het grdient between niml nd environment in order to llow greter het dissiption. Our performnce nd TT dt suggest preventing cttle from getting too hot during the dy by providing externl cooling in the morning is superior to providing externl cooling in the fternoon. However, providing externl cooling in the fternoon tended to enhnce intke during very hot environmentl conditions. Figure 5. Effect of wter ppliction to feedlot mounds on tympnic temperture of steers. b Vlues within time with different superscripts differ (P <.05). 1 Shne Dvis, grdute student, Animl Science; Terry Mder, professor, Animl Science; Wnd Cerkoney, reserch technicin. The Reltionship of the Chrcteristics of Feedlot Pens to the Percentge of Cttle Shedding Escherichi coli O157:H7 Within the Pen Dvid Smith Mrk Blckford Spring Younts Rodney Moxley Jeff Gry Lur Hungerford Todd Milton Terry Klopfenstein 1 The food-borne pthogen Escherichi coli O157:H7 ws commonly found in pens of feedlot cttle, nd the percentge of cttle shedding the orgnism my hve been influenced by the pen environment. Summry This study ws designed to discover reltionships between chrcteristics of feedlot pens nd the percentge of cttle shedding Escherichi coli O157:H7. Twenty-nine pens from five Midwestern feedlots were ech smpled once between June nd September, Feces were collected from ll cttle in ech pen. E. coli O157:H7 ws isolted from the feces of 714 of 3162 cttle tested (23%), including t lest one niml from ech of the 29 pens. Pen prevlence did not differ between feedyrds, but did vry widely within feedyrds. Muddy pens were more likely to hve higher pen prevlence thn norml pens. Introduction Escherichi coli bcteri re commonly found s norml inhbitnts of the intestinl trcts of humns nd nimls. Unfortuntely, some strins including E. coli O157:H7, though generlly hrmless for cttle, crry trits tht llow them to cuse serious foodborne disese in humns. Mny segments of the food industry hve dopted the principles of hzrd-nlysis-criticl-control-points (HACCP) to minimize the likelihood tht food will be contminted with potentilly dngerous pthogens. Unfortuntely, there is insufficient knowledge of the epidemiology nd (Continued on next pge) Pge Nebrsk Beef Report

82 ecology of E. coli O157:H7 to design nd implement HACCP-bsed food sfety progrms in cttle feedyrds. Cttle in feedlots rrely re hndled s individuls. Most conceivble control points for reducing humn foodborne pthogens in feedlot cttle would be directed towrds pens of cttle. Therefore, epidemiologic studies with the objective of identifying mngeble fctors (control points) to reduce humn food-borne pthogens in the feedlot should relte the chrcteristics nd pthogen sttus of mnged groups of cttle (pens), rther thn chrcteristics of cttle s individuls. The objective of this study ws to describe the percentge of cttle shedding E. coli O157:H7 in feces within Midwestern feedlot pens nd to identify potentil risk fctors for pen prevlence. Study design Procedure voluntrily prticipte in the study. The one time cttle cpcity in these feedyrds rnged from 3,000 to 12,000 hed; pproximtely 40,000 hed collectively in pens of 50 to 300 hed. Pens were open-dirt lots, mintined by scrping, typiclly once per month. The feedlots involved in this study fed primrily dry-rolled corn, high-moisture corn, wet corn gluten feed, wet distillers grins, lflf hy, corn silge, nd other byproducts. Cttle pens were selected from the 5 commercil feedyrds t the time of routine re-processing. Pens were bypssed, or pens with fewer cttle were chosen for smpling, during weeks when more pens were vilble thn could be mnged by the culturing cpcity of the lbortories. Smpled pens rnged from 36 to 231 (medin 107) cttle. At smpling, cttle hd been in the feedyrds 19 to 108 (medin 51) dys nd the men body weight per pen rnged from 764 to 1175 lbs (medin 930 lbs). Microbiology Culture methods were specific to the type of smple but included selective enrichment nd immunomgnetic seprtion. Isoltes were confirmed by stndrd methods including PCR. Methods for recovery of E. coli O157:H7 from feces were modifictions of those recently reported (Legreid et l., Epidemiol Infect. pp ). Sttisticl methods The dependent vrible ws the penprevlence of E. coli O157:H7 defined s the percentge of cttle within pen from which the orgnism ws isolted from feces. The correltion between the mgnitude of pen-prevlence of E. coli The study design ws cross-sectionl observtionl t the level of the feedyrd pen. The percentge of cttle within pen shedding detectble levels of E. coli O157:H7 ws described nd compred to concurrent chrcteristics of the feedlot pen relting to the cttle nd the pen environment. Approximtely 30 g of feces ws collected from the rectums of ll cttle within ech pen while they were restrined in hndling chute for routine mngement procedures (re-implnting). Concurrent smples were collected of wter from wter tnks, nd prtilly consumed feed from feedbunks of the sme pens. Concurrent informtion ws collected bout chrcteristics of the pen tht my be risk fctors for the prevlence of cttle shedding E. coli O157:H7. These fctors included number of cttle, dys on feed, verge body weight, clss nd sex of cttle, culture results from wter or feed, wter-tnk temperture nd ph, nd subjective ssessments of pen condition nd wter-tnk clenliness. Source of cttle Five feedyrds, typicl of commercil feedlots in the region, were sked to Percent of pen shedding O157:H Feedlot code Figure 1. Percentge of cttle shedding detectble Escherichi coli O157:H7 in ech of 29 pens of feedlot cttle in five Midwestern feedyrds. Prevlence levels of fecl-shedding for individul pens re represented by brs rrnged in order of incresing prevlence by feedyrds of origin. Tble 1. Continuous or ordinl vribles describing 29 feedlot pens from 5 Midwestern US feedyrds nd the correltion of the vrible to the percentge of cttle within pens found shedding Escherichi coli O157:H7 in the feces. Rnge of vlues Spermn s rnk Vrible (Medin) correltion coefficient P-vlue Pen size (107) r = Dys in the feedyrd (51) r = Averge body weight (930) r = Temperture of wter in tnk (61.1) r = ph of wter in tnk (7.2) r = Clenliness of wter in tnk 1-5 (3) r = ph of feed in bunk (4.8) r = Nebrsk Beef Report Pge 82

83 Percent of pen shedding O157:H Figure 2. Percentge of cttle shedding detectble Escherichi coli O157:H7 in pens subjectively clssified by pen environment s: 1-dry nd dusty, 2-norml condition, 3-wet nd muddy. Compred to pens with norml environmentl conditions, pens clssified s wet nd muddy hd significntly greter pen prevlence of E. coli O157:H7. O157:H7 (rnk order of pen-prevlence) nd vribles representing pen chrcteristics which were t lest ordinl ws tested using Spermn s rnk correltion. Assocition of the mgnitude of pen-prevlence with ctegoricl vribles ws tested using non-prmetric methods. Results E. coli O157:H7 ws isolted from the feces of 714 of 3162 cttle tested (23%), including t lest one niml from ech of the 29 pens. The pen prevlence of cttle shedding detectble levels of the orgnism rnged from 0.7% to 79.8% (medin 17.1%). Feedyrds did not differ by pen prevlence (Kruskl- Wllis P=0.81); however, within ech feedyrd the pen prevlence differed widely (chi squre P<0.001; Figure 1). E. coli O157:H7 ws recovered from the wter tnks of seven pens nd the feed from the bunk of one pen. Pen prevlence ws not ssocited with recovery of the gent from feed Pen Condition Pen Condition Score (Wilcoxon rnk sums P=0.31), or wter (Wilcoxon rnk sums P=0.15). Pen prevlence ws not correlted with the temperture, ph, or clenliness of wter from the wter tnks, or ph of the feed, number of cttle, men body weight or number of dys in the feedyrd (Tble 1). The condition of the pen surfce, subjectively evluted s dry, norml, or wet, ws ssocited with the level of pen prevlence (Kruskl-Wllis P<0.05; Figure 2). Specificlly, wet pen conditions were ssocited with higher pen prevlence thn pens in norml condition (Wilcoxon rnk sums, P=0.01). The prevlence of fecl shedding within feedlot cttle herds nd pens hs been reported to be low. However, the relibility of E. coli O157:H7 prevlence estimtes in cttle my vry by the dignostic method employed, the number of cttle smpled nd the type of smples collected. The overll 23 percent of fecl shedding observed in this study is consistent with other reports suggesting tht t times the orgnism my be widespred in beef cttle popultions. For exmple, in recent Cndin study, the orgnism ws recovered from 19.7 percent of fecl smples collected t slughter from yerling cttle nd cull cows during the summer months (Vn Donkersgoed et l Cndin Vet J. pp ). The pen prevlence of fecl shedding did not differ between the five feedyrds. This finding suggests tht E. coli O157:H7 my be ubiquitous to feedlot cttle popultions. In multistte crosssectionl study, reserchers cultured the feces of 120 cttle ech (4 pens x 30 fecl pts) in 100 feedyrds (Hncock et l J Food Prot. pp ). This smpling strtegy my prevent detection of low prevlence pens. Despite low overll prevlence of shedding (1.6%), E. coli O157:H7 ws found in 61% of the feedyrds surveyed. Other surveys, using serology (Legreid et l Conf Res Workers Anim Dis P26) nd bcteril culture of feces (Srgent et l Conf Res Workers Anim Dis Abstrct 41), suggest tht exposure to E. coli O157:H7 is widespred nd most beef cttle hve been exposed to the orgnism before wening. Becuse of commingling, widespred exposure of cttle to E. coli O157:H7 fter rrivl in lrge cttle feedlots is plusible, t lest during certin sesons. Cttle recently rriving in the feedyrd hve been demonstrted to be t greter risk for shedding E. coli O157 thn cttle on feed longer (Drgtz et l J Food Prot pp ). All pens we observed hd some cttle shedding the orgnism in the feces. In spite of the pprent ubiquity of the orgnism, the pen-prevlence of cttle shedding E. coli O157:H7 vried gretly within ech feedyrd. Pens with high nd low prevlence of fecl shedding were observed in ech feedyrd. Fctors tht explin the vribility in penprevlence of E. coli O157:H7 fecl shedding my be risk fctors tht could be mnged s control points in HACCP-bsed feedlot production food sfety progrm. The environmentl condition of the pen ws the only pen chrcteristic tht ws ssocited with pen prevlence. (Continued on next pge) Pge Nebrsk Beef Report

84 Pens with the gretest percentge of cttle shedding E. coli O157:H7 were more likely to be wet nd muddy t the time of smple collection. Pens with dusty conditions were intermedite in the percentge of cttle shedding the orgnism. The ssocition between the environmentl condition of pen nd the percentge of cttle shedding E. coli O157:H7 seems plusible. Compred to the norml pen conditions, muddy or dusty conditions would be expected to fcilitte fecl-orl trnsmission of enteric gents becuse of greter opportunity for the gent to move with wter or dust prticles. It is unlikely tht selection bis ws introduced by voluntry recruitment of the feedyrds or selection of cttle pens by convenience. There ws no prior knowledge of the E. coli O157:H7 sttus of ny of the feedyrds. Pens were selected for inclusion in the study with considertion for the feedyrds re-implnting schedule nd the worklod of the lbortories. When there ws n option, pens with fewer cttle were preferentilly chosen for study to minimize costs. Pens were selected without knowledge of the results from previous pens in the feedyrds. The results of this study suggest tht E. coli O157:H7 should be considered n ubiquitous orgnism in pens of feedlot cttle nd tht fctors in the pen environment my help to explin the prevlence of cttle shedding the orgnism. The limited time-period of the study (summer months) nd the cross-sectionl nture of the study did not permit observing the effect of time dependent vribles on the outcome of pen prevlence. It would be interesting to observe chnges in pen prevlence over time s pen conditions chnge. 1 Dvid Smith, ssistnt professor, Veterinry nd Biomedicl Sciences, Lincoln; Mrk Blckford, grdute student, Animl Science, Lincoln; Spring Younts, grdute student, Veterinry nd Biomedicl Sciences, Lincoln; Todd Milton, ssistnt professor, Animl Science, Lincoln; Rodney Moxley, professor, Jeff Gry, ssistnt professor, Veterinry nd Biomedicl Sciences, Lincoln; Lur Hungerford, ssocite professor, Gret Plins Veterinry Eductionl Center, Cly Center; Terry Klopfenstein, professor, Animl Science, Lincoln. A Dignostic Strtegy to Clssify Pens of Feedlot Cttle by the Prevlence of Escherichi coli O157:H7 Fecl Shedding Dvid Smith Spring Younts Mrk Blckford Rodney Moxley Jeff Gry Lur Hungerford Todd Milton Terry Klopfenstein 1 This dignostic strtegy cn be used in food-sfety reserch or s monitoring tool in niml production food-sfety progrms to clssify feedlot pens by the percentge of cttle shedding Escherichi coli O157:H7. Summry This study evluted two pen testing strtegies to predict the percentge of cttle in pen shedding detectble E. coli O157:H7. Culture of composite fecl smple most ccurtely detected pens with 37% or more cttle shedding E. coli O157:H7 in feces. A new pen test device most ccurtely detected pens with 16% or more individuls shedding. The likelihood of detecting E. coli O157:H7 with either method incresed s pen prevlence incresed. If both pen-level test methods were used together, pens could be clssified s high, medium or low prevlence with less lbor nd expense thn testing individul cttle. Introduction The principles of hzrd-nlysiscriticl-control-points (HACCP) were developed to minimize the likelihood tht food will be contminted with potentilly dngerous pthogens. Idelly food-sfety would be mximized if HACCP principles were pplied t ll levels of food production nd processing. Unfortuntely, there is insufficient knowledge of the epidemiology nd ecology of E. coli O157:H7 to design nd implement HACCP-bsed food sfety progrms in cttle feedyrds. Reserch or development of on-frm HACCP progrms to control E. coli O157:H7 in feedlot production systems hve been hmpered by difficulty in determining the infection sttus of cttle t ny point in time. The difficulty in dignosis results becuse infection with E. coli O157:H7 in cttle occurs without clinicl signs, except in clves, nd becuse there is lck of field-vlidted methods to monitor livestock for food sfety pthogens. Determining if individul live cttle re shedding E. coli O157:H7 is expensive nd imprcticl. For exmple, culture of the feces from most, if not ll, nimls in feedlot pen requires considerble lbor nd supplies. Hndling finished cttle prior to shipping is not desirble becuse of the loss in vlue to cttle due to shrink, drk cutters nd bruising. It my be possible to control E. coli O157:H7 in feedlots without knowing the infection sttus of individul cttle becuse control points or interventions for reducing humn foodborne pthogens in feedlot cttle would most likely be directed towrds pens of cttle. Therefore, the E. coli O157:H7 sttus of pens of feedlot cttle is n importnt outcome for feedlot production food sfety reserch nd HACCP monitoring. Reserch nd development of HACCP-bsed feedlot food sfety progrms could dvnce if pens of cttle, rther thn individuls, could be ccurtely nd economiclly clssified by 2001 Nebrsk Beef Report Pge 84

85 Pen-prevlence (%) Pen Identifiction both tests negtive only pen-test positive pen-test nd feces positive Figure 1. The reltionship between the Escherichi coli O157:H7 culture results of the pen-test device, composite fecl smple collected from the pen nd the percent of cttle in the pen shedding detectble levels of the orgnism in rectl feces. the level of fecl shedding of E. coli O157:H7. Such pen-test could serve s monitoring tool in feedlot production food-sfety progrms, nd would llow reserchers to test potentil interventions, or look for feedlot production methods relted to the presence or bsence of food-borne pthogens. The objective of this study ws to evlute dignostic strtegies to efficiently identify pens of feedlot cttle with high prevlence of cttle shedding E. coli O157:H7. Procedure Twenty-nine feedlot pens from five Midwestern feedlots, rnging in size from 36 to 231 (medin 107) cttle, were ech studied once between June nd September, 1999 (Smith et l Beef Report). Seven pen-test devices tht cttle could rub, lick or chew were plced in the pens the evening prior to smple collection. The morning of smpling, feces were collected from the rectums of ll cttle in ech pen nd concurrent smples were collected of pen-test devices nd single composite smple of 20 fresh fecl pts from the pen surfce. Culture methods were specific to the type of smple but included selective enrichment nd immunomgnetic seprtion. Isoltes were confirmed by stndrd methods including PCR. Non-prmetric sttisticl methods were used to test either rnk differences or rnk correltions between pen-level clssifictions nd the results of individul niml testing. Results Escherichi coli O157:H7 ws isolted from t lest one niml in ech of the 29 pens. The percentge of cttle shedding detectble levels of the orgnism within pen rnged from 0.7% to 79.8% (medin 17.1%). E. coli O157:H7 ws recovered from t lest one pen-test device from 15 pens nd from the composite fecl smples of eight pens (Figure 1). Recovery of E. coli O157:H7 from t lest one pen test device or from the composite fecl smple ws most likely to occur from the pens with higher prevlence (Wilcoxon rnk sums P=0.001). The pen-test devices nd composite feces were evluted singly s dignostic tools to differentite high prevlence pens from low prevlence pens. The new pen-test device most ccurtely detected s positive (gretest percentge of pens clssified correctly) pens with 16% or greter prevlence (pen-level sensitivity = 82%, pen-level specificity = 92%). Culture of composite feces most ccurtely detected s positive pens with 37% percent or higher prevlence (penlevel sensitivity = 86%, pen-level specificity = 91%). Informtion from culture of the pentest devices nd the composite feces ws combined to clssify pens by three levels of fecl shedding prevlence. Pens were clssified s high prevlence if E. coli (Continued on next pge) Pge Nebrsk Beef Report

86 O157:H7 ws recovered from the composite fecl smple; pens were clssified s medium prevlence if the orgnism ws recovered from the device, but not from the composite feces; pens were clssified s low prevlence if the orgnism ws not recovered from the device or the composite feces. This clssifiction scheme correlted well (Spermn s r = 0.76, P<0.0001) with the pen-prevlence determined by culturing the feces from individul cttle. Pens clssified s high prevlence hd significntly higher rnkings in pen-prevlence thn pens clssified s medium prevlence (P=0.05) or low prevlence (P=0.0006), nd pens clssified s medium prevlence hd significntly higher rnkings in pen-prevlence thn pens clssified s low prevlence (P=0.005). The premise of the pen-test ws to culture few devices from which mny cttle in pen could hve contributed orgnisms. Culture of the pen-test devices lone or in prllel with culture of composite fecl smple my be dignosticlly efficient strtegy to chrcterize E. coli O157:H7 fecl shedding in feedlot pens. This dignostic strtegy my be useful s reserch tool or s monitoring tool in the development of niml production food sfety progrms. 1 Dvid Smith, ssistnt professor, Veterinry nd Biomedicl Sciences, Lincoln; Spring Younts, grdute student, Veterinry nd Biomedicl Sciences, Lincoln; Mrk Blckford, grdute student, Animl Science, Lincoln; Todd Milton, ssistnt professor, Animl Science, Lincoln; Rodney Moxley, professor, Veterinry nd Biomedicl Sciences, Lincoln; Jeff Gry, ssistnt professor, Veterinry nd Biomedicl Sciences, Lincoln; Lur Hungerford, ssocite professor, Gret Plins Veterinry Eductionl Center, Cly Center; Terry Klopfenstein, professor, Animl Science, Lincoln. Influence of Restricted Intke nd Reduced Dietry Strch on Colonic ph nd E. coli Prevlence Tim Loy Csey Wilson Doreen Biley Mrk Blckford Terry Klopfenstein Rod Moxley Dvid Smith Spring Younts 1 A finishing diet low in strch incresed fecl ph, lowered VFA, nd reduced numbers of cid-resistnt E. coli shed in the feces. Summry Ninety feedlot steers were used to test the effects of reducing dietry strch nd intke on colonic ph, VFA, totl nd cid-resistnt coliform nd E. coli popultions, nd E. coli O157:H7 shedding. When corn brn nd wet corn gluten feed (WCGF), or high moisture corn nd WCGF were substituted for dry rolled corn, colonic ph incresed while VFA concentrtion decresed. The corn brn nd WCGF diet reduced cid-resistnt E. coli shedding. Restricting intke incresed colonic ph nd decresed VFA con- centrtion, but did not ffect cidresistnt E. coli shedding. Prevlence of E. coli O157:H7 ws not ffected by diet or intke. Introduction Enterohemorrhgic Escherichi coli O157:H7 is bcterium found commonly in the intestinl trct of livestock tht cn cuse severe illness nd deth in humns. More thn 100 outbreks of E. coli O157:H7 hve been reported since 1982, 52% of which hve been linked to foods derived from cttle. Besides its ubiquitous distribution in livestock, other noteworthy chrcteristics of E. coli O157:H7 re its low infective dose for humns nd its cid resistnce. Becuse it cn thrive under low ph conditions, undigested feed tht is fermented in the colon my fcilitte growth of E. coli O157:H7 nd ultimtely increse the numbers of the orgnism being shed in the feces. High grin finishing diets my result in lrge mounts of undigested strch reching the colon. Becuse of this, it hs been suggested tht feeding hy insted of grin would decrese the mount of strch reching the colon, increse colonic ph nd decrese the numbers of cid-resistnt E. coli being shed in the feces. In 1998, it ws reported tht switching cttle from grin-bsed diet to hy four dys prior to slughter reduced the prevlence of both generic nd cid resistnt E. coli. A similr study conducted t the University of Nebrsk confirmed these results. When steers consuming dry-rolled corn, high-moisture corn, or wet corn gluten feed were switched to lflf hy for five dys, cid-resistnt E. coli popultions in the feces were reduced by 99% (2000 Nebrsk Beef Report, pp ). Feeding hy t the end of the feeding period my not be fesible mngement prctice for cttle feeders. However, if reducing the mount of fermenttion in the colon is the key to reducing the numbers of cid-resistnt E. coli being shed in the feces, more prcticl pproches my be vilble. High moisture corn, wet corn gluten feed (WCGF) nd corn brn re feedstuffs used commonly in Nebrsk feedlots, nd ech would be expected to result in less undigested strch reching the colon. Therefore, the objectives of this tril were to determine the effect of 2001 Nebrsk Beef Report Pge 86

87 Tble 1. Composition of diets. Tretment Ingredient, %DM High Med Low Dry rolled corn High moisture corn Corn brn Wet corn gluten feed Alflf hy Molsses 3.00 Supplement Tble 2.Effect of diet on colonic digest smples. Dietry tretment Item High Med Low Colonic ph 6.90 c 7.25 d 7.52 e VFA, mmol/g feces f,g f g Totl coliform, log b Acid resistnt coliform, log b c 2.98 d 2.64 d Totl E. coli, log b c 5.71 d 6.35 c Acid resistnt E. coli, log b f 4.06 g 3.86 g High = dry rolled corn, Med = high moisture corn nd WCGF, Low = corn brn nd WCGF. b Bcteril numbers shown in log 10 colony forming units / g feces. c,d,e Mens within row differ (P <.01). f,g Mens within row differ (P <.05). VFA, mm/g feces VFA, mm/g feces VFA, mm/g feces % High Med Low Dy of smpling 65% Dy of smpling 45% Dy of smpling Figure 1. Effect of dy on colonic VFA concentrtion within intke level. DRC = dry-rolled corn, HMC = high-moisture corn nd wet corn gluten feed, nd Brn = corn brn nd wet corn gluten feed. 100% = d libitum, 65% nd 45% = intke restricted to 65% nd 45% of d libitum, respectively. replcing dry-rolled corn with either high-moisture corn nd WCGF or corn brn nd WCGF on colonic ph nd voltile ftty cid concentrtion, s well s coliform bcteri nd E. coli being shed in feces. Additionlly, we wished to determine the effects of limiting intke of ech of these diets. Tretment diets were fed t the end of the finishing phse, with the objective being to reduce shedding of E. coli prior to rrivl t the pcking plnt without hmpering performnce. Procedure Ninety crossbred steers (BW = 1198 lb) were used to test the effects of finishing diet nd level of intke on colonic ph nd VFA content, s well s coliform bcteri nd E. coli shedding. The project ws designed s 3 x 3 fctoril, with three diets offered t three levels of intke. Clves were rndomly ssigned to tretment nd llotted to one of 18 pens (5 hed/pen; 2 pens/ tretment). Tretment diets (Tble 1) were formulted to supply vrying mounts of unfermented strch reching the colon, nd were bsed on dry-rolled corn (High), high-moisture corn nd wet corn gluten feed (Med), or combintion of corn brn nd wet corn gluten feed (Low). Diets were offered free choice (100%), or restricted to either 65% or 45% of full consumption for 10 dys. Cttle were penned together within diet type for 14 dys prior to initition of the tril to estblish d libitum levels of intke. Fecl smples were collected from the rectum of ech individul on ten consecutive dys, nd nlyzed for ph, cette, butyrte, isobutyrte, propionte, isovlerte nd totl VFA concentrtion. Totl coliform bcteri, totl E. coli, nd cid-resistnt coliforms nd E. coli were quntified. The presence of E. coli O157:H7 ws lso determined. Results Anlysis of fecl smples collected on dy 1 (Tble 2) represent the effect of d libitum consumption of the tretment diets. Cttle consuming diets contining (Continued on next pge) Pge Nebrsk Beef Report

88 WCGF hd higher (P <.01) colonic ph vlues thn those on DRC-bsed finishing rtion. Replcing HMC with corn brn further rised (P <.01) colonic ph. Voltile ftty cid concentrtion of colonic digest did not differ (P >.05) between the DRC nd HMC-bsed diets. The corn brn diet did reduce (P <.05) the mount of VFA in the colon. The totl number of coliform bcteri isolted from rectl grb smples collected on dy 1 did not differ (P >.05) between diets. Acid-resistnt coliforms were reduced (P <.01) by the inclusion of WCGF. The totl number of E. coli cultured ws lower (P <.01) for cttle consuming the HMC diet compred to the other tretments, nd the corn brn tretment tended (P =.06) to be lower thn DRC. The number of cid-resistnt E. coli being shed in the feces ws lower (P <.05) in smples collected from clves consuming diets contining WCGF. Once intke restrictions were imposed, level of intke significntly (P <.01) influenced colonic ph. Cttle on d libitum intke hd n verge colonic ph of Tht incresed to 7.35 nd 7.46 for 65% nd 45% restriction, respectively. Becuse of the inclusion of limestone in the diets, nd its potentil to ct s buffer in the colon, colonic VFA concentrtion my be better indictor of microbil ctivity in the hind gut, rther thn ph. Restricting intke decresed (P <.01) the mount of VFA from 150, to 131, nd 110 mmol/g, for 100%, 65, nd 45% intke, respectively. Intke level did not (P =.83) ffect the numbers of cidresistnt E. coli being shed in feces. The number of clves shedding E. coli O157:H7 rnged from 0% to 18% over the 10-dy smpling period, nd prevlence ws not ffected by diet. Level of intke lso hd no significnt impct on O157:H7, though numericl differences were evident. Across dys nd diets, 12% of d libitum, 14% of 65% intke, nd 5% of 45% intke clves were positive for O157:H7. In order for tretments to yield sttisticl differences cid-resistnt E. coli, log 10 cid-resistnt E. coli, log 10 cid-resistnt E. coli, log % High Med Low Dy of smpling 65% Dy of smpling 45% Dy of smpling Figure 2. Effect of dy on cid-resistnt E. coli numbers cultured from colonic digest. DRC = dryrolled corn, HMC = high-moisture corn nd wet corn gluten feed, nd Brn = corn brn nd wet corn gluten feed. 100% = d libitum, 65% nd 45% = intke restricted to 65% nd 45% of d libitum, respectively. in the presence or bsence of E. coli O157:H7, it my be necessry to hve lrger smple sizes thn the numbers used in this study. Replcing dry-rolled corn with highmoisture corn nd WCGF, or corn brn nd WCGF rised colonic ph nd reduced VFA concentrtions in feedlot steers. Restricting intke to 65% nd 45% of d libitum hd similr effect. A WCGF nd corn brn-bsed diet tended to reduce numbers of cidresistnt E. coli shed in the feces. Prevlence of E. coli O157:H7 in feces ws not ffected by diet or level of intke. 1 Tim Loy, Csey Wilson, Doreen Bily, reserch technicins; Terry Klopfenstein, professor niml science; Rod Moxley, professor, Dve Smith, ssistnt professor, Spring Younts, grdute ssistnt; Veterinry nd Biomedicl Sciences Nebrsk Beef Report Pge 88

89 Phosphorus nd Nitrogen-Bsed Beef Cttle Mnure or Compost Appliction to Corn Bhmn Eghbll 1 Nitrogen nd phosphorus-bsed mnure nd compost pplictions resulted in similr corn yields cross four yers but soil P ccumultion ws much greter for N-bsed thn P-bsed ppliction. Summry This study ws conducted to evlute effects of P nd N-bsed mnure nd compost pplictions on corn yield nd soil P level. Annul or biennil mnure or compost ppliction resulted in corn grin yields similr to those with chemicl fertilizer ppliction. P-bsed mnure or compost ppliction resulted in similr corn grin yield but significntly less soil P build-up thn N-bsed tretments. Estimted N vilbility ws 40% for mnure nd 15% for compost in the first yer nd ws 18% for mnure nd 8% for compost in the second yer fter ppliction. Introduction Beef cttle feeding is concentrted in the Centrl nd Southern Gret Plins. At ny one time, there re t lest 10 million hed of beef cttle on feed in the United Sttes. Approximtely 585,000 tons of N, 173,000 tons of P nd 530,000 tons of K re excreted nnully in this beef feedlot mnure. Crbon in mnure is likely to hve fr greter vlue thn the nutrients it contins if pplied to low orgnic mtter or eroded soil. Composting mnure is useful method of producing stbilized product tht cn be stored or spred with little odor, weed seeds, pthogens, or fly breeding potentil. Composting lso hs some disdvntges. Study conducted by the uthor indicted 20-40% loss of totl N nd 46-62% loss of totl C during composting of beef cttle feedlot mnure, s well s significnt losses of K nd N (> 6.5% of totl K nd N) in runoff from composting windrows during rinfll. Mnure or compost ppliction to provide for corn N requirements my gretly increse soil levels of P since the N:P rtios of beef cttle feedlot mnure nd composted mnure re significntly smller thn N:P uptke rtios of most crops. The N:P rtio for feedlot mnure is bout 2.5 nd is 2 for composted mnure while N:P grin uptke rtios of winter whet, corn, nd grin sorghum re round 4.5, 5.9, nd 4.5, respectively. The increse in soil P level cn increse P loss in runoff, which hs been ssocited with eutrophiction (lge bloom nd oxygen depletion) of rivers nd lkes. The objective of this study ws to evlute the effects of ppliction frequency nd N nd P-bsed rtes of mnure nd compost ppliction on corn grin yield nd soil P level. Procedure A drylnd experiment ws initited in 1992 on Shrpsburg silty cly lom soil under drylnd conditions t the University of Nebrsk Agriculturl Reserch Center ner Med, Neb. The study re hd Bry nd Kurtz No.1 soil P test of 69 ppm, which is considered very high in Nebrsk, nd ph of Tble 1. Chrcteristics of beef cttle feedlot mnure nd composted feedlot mnure pplied in four yers t Med, NE. Nutrients nd sh contents re on dry weight bsis. Yer nd Totl Totl Ash Wter NO 3 -N NH 4 -N EC ph source N P content % ppm m mho/cm 1992 Mnure Compost Mnure Compost Mnure Compost Mnure Compost Electricl conductivity (EC) nd ph were determined on 2:1 wter to dry mnure or compost rtio. Tble 2. Composted nd non-composted mnure dry weight ppliction in four yers t Med, Neb. Dry weight Tretment tons/cre Mnure for N Mnure for P Mnure for N / 2Y Mnure for P / 2Y Compost for N Compost for P Compost for N / 2Y Compost for P / 2Y Fertilizer 2Y indictes biennil mnure or compost ppliction. Pge Nebrsk Beef Report

90 Grin Yield (bu/cre) CK CN CP CN CP FR MN MP MN MP 2Y 2Y 2Y 2Y Tretment Figure 1. Corn grin yield for ten tretments in four yers t Med, Neb. Ech verticl br is stndrd devition of tht men. CN is N-bsed compost, CP is P-bsed compost, MN is N-bsed mnure, MP is P-bsed mnure, FR is fertilizer, CK is check, nd 2Y indictes biennil ppliction. 6.2 in the top 6 inches. The experimentl design ws rndomized complete block with four replictions. The 10 tretments pplied included nnul or biennil mnure or compost ppliction bsed on N or P removl of corn (135 lb N/cre nd 53 lb P 2 O 5 /cre for n expected yield level of 150 bu/cre) nd fertilized nd unfertilized checks. Fertilizer ppliction ws mde in the spring ech yer. If necessry, the P-bsed tretments (nnul or biennil ppliction) lso received N fertilizer s mmonium nitrte (34-0-0, N-P-K) in the spring so tht totl of 135 lb N/cre ws vilble to the crop. Beef cttle feedlot mnure (collected in November) nd composted feedlot mnure were pplied in November 1992 bsed on the ssumption tht 40, 20, 10 nd 5% of the N nd P in mnure or compost will become plnt vilble in the first, second, third nd fourth yer fter ppliction, respectively. The first yer N vilbility ssumption from compost ws found to be too high so vilbility ssumptions were chnged to 20, 20, 10, 5% in the first, second, third nd fourth yer fter compost pplictions in 1993, 1994 nd Biennil mnure or compost pplictions were mde to provide 135 lb N/cre for N-bsed nd 53 lb P 2 O 5 /cre for P-bsed rtes in the second yer fter ppliction bsed on the ssumptions given bove. Residul N nd P vlues from previous yers were considered when mnure or compost were pplied. Mnure or compost ppliction ws mde in lte utumn (November or December) fter corn hrvest. Mnure nd compost were pplied by hnd to plots 40 feet long nd 15 feet wide (six corn rows). The chrcteristics nd mounts of mnure nd compost pplied for ech tretment re given in Tbles 1 nd 2. Mnure nd compost were pplied nd disked-in within two dys fter ppliction. Corn (Pioneer 3394) ws plnted t seeding rte of 19,000 seeds/cre nd row spcing of 30 inches. The plnting dtes were My 21, 1993, My 10, 1994, My 24, 1995, nd My 21, Corn ws hrvested by hnd in October (middle 2 rows, 20 feet long) of ech yer nd grin yield determined. The reported yields re djusted to 15.5% moisture content. Soil smples were collected from ll plots ech yer fter hrvest. The surfce soil (0 to 6 inches) smples were nlyzed for Bry nd Kurtz No.1 soil P test to evlute the effects of mnure, compost nd fertilizer ppliction on the soil P level. The mounts of rinfll from June 1 to Aug. 31 for the bove yers were 23.4, 15.9, 4.2, nd 8.5 inches for 1993, 1994, 1995 nd 1996, respectively. Grin yield Results There ws significnt yer by tretment interction for corn grin yield. The reltive differences mong tretments were different for ech yer (Figure 1). Grin yields for ll tretments were greter thn the check. Grin yields for the mnure nd compost tretments were similr to those for the fertilizer tretment in ll four yers (Figure 1). This indictes tht nnul or biennil (Continued on next pge) 2001 Nebrsk Beef Report Pge 90

91 mnure or compost ppliction cn provide dded nutrients to corn, similr to fertilizer ppliction, with dded benefits of orgnic mtter nd micronutrients ddition to the soil. Phosphorus-bsed mnure or compost ppliction, with dditionl N s fertilizer, produced similr corn grin yields to those for the N-bsed nd fertilizer tretments. Nitrogen use efficiency ws greter for mnure thn compost ppliction. The estimted first-yer N vilbility from mnure N ws 40%, nd ws 15% for compost ppliction. Second-yer N vilbility estimtion ws 18% for mnure nd 8% for compost ppliction. Nitrogen vilbility from compost ws less thn the expected 20%. Smll frctions of N re vilble in the third nd fourth yer fter ppliction (usully <10%). The mnure or compost N remining fter the fourth yer become portion of soil-n nd smll frction becomes plnt vilble ech yer. Soil Phosphorus The results indicte tht surfce soil (top 6 inches) phosphorus level ws gretest for the biennil N-bsed compost ppliction nd ws lest for the check plot (Figure 2). There ws significnt yer by tretment interction for soil P level. Soil P levels for ll N-bsed tretments were greter thn those for the check plots (Figure 2). Annul P-bsed mnure nd compost ppliction hd P levels tht were similr to the originl soil P level of 69 ppm even fter four yers of mnure nd compost ppliction. Even though the N-bsed mnure nd compost tretments hd soil P levels similr to those for the fertilizer tretment in 1993, they hd higher soil P levels thn the fertilizer tretment in lter yers (Figure 2). Biennil P-bsed mnure or compost ppliction resulted in greter soil P build-up thn did nnul P-bsed mnure or compost pplicture. This is becuse of the greter mount of mnure or compost pplied every other yer. Nitrogen-bsed mnure or compost ppliction resulted in vilble soil P levels tht were significntly greter thn those for the P-bsed Bry nd Kurtz No. 1 P (ppm) CK CN CP CN CP FR MN MP MN MP 2Y 2Y 2Y 2Y Tretment Figure 2. Surfce soil (0-6 in) P levels for ten tretments in four yers t Med, Neb. Ech verticl br is stndrd devition of tht men. CN is N-bsed compost, CP is P-bsed compost, MN is N-bsed mnure, MP is P-bsed mnure, FR is fertilizer, CK is the check, nd 2Y indictes biennil ppliction. mnure or compost ppliction, fertilizer, or check tretments. After four yers of ppliction, nnul P-bsed mnure or compost tretments hd soil P levels similr to the originl soil P level before tretment ppliction. Phosphorus-bsed mnure or compost ppliction strtegy cn increse the distnce mnure nd compost need to be huled nd hence increse the ppliction cost. Therefore, P-bsed ppliction should be used in sites vulnerble to P runoff losses. A recently developed P Risk Assessment Index cn be used to determine which sites re vulnerble to P runoff losses. Nitrogenbsed mnure nd compost pplictions cn be used in res where the potentil for P runoff loss is miniml. 1 Bhmn Eghbll is soil scientist with the USDA-Agriculturl Reserch Service, Lincoln, NE, nd n djunct ssocite professor of Agronomy t the University of Nebrsk-Lincoln. Pge Nebrsk Beef Report

92 Composting of Feedlot nd Diry Mnure: Compost Chrcteristics nd Impct on Crop Yields Glen Erickson Terry Klopfenstein Wlker Luedtke Mrk Schroeder Chuck Frncis Gry Lesoing 1,2 Compost fertiliztion incresed yields of irrigted corn nd soybens, drylnd corn, whet, nd grin sorghum. The incresed yield offset ppliction costs for ll crop rottions except soybens. Summry Since 1993, pproximtely 17,600 tons of beef feedlot nd diry compost hve been spred on 1,100 cres. Crop yields were mesured to determine the impct of one-time compost ppliction by using no-compost check strips in lrge-scle production fields. Adding compost to irrigted corn, irrigted soybens, nd drylnd corn cres significntly incresed yields, with four-yer verge increses of 2.3, 1.5, nd 2.7%, respectively. For ll crops mesured, the response to compost ws gretest the first yer following ppliction nd declined linerly in subsequent yers. The incresed yield from compost ppliction offsets spreding costs using verge prices for crops. Introduction Mnging mnure nd nutrients is becoming incresingly importnt for griculturl producers. For these resons, numerous projects were initited t the University of Nebrsk to help producers become more wre of the chllenges with mnging mnure, nd lso the costs ssocited with nutrient mngement. The primry focus of this rticle is to summrize compost chrcteristics nd verge yield responses from one-time compost ppliction to irrigted corn nd soybens, or drylnd corn, soybens, whet nd grin sorghum. Procedure Composting ws initited in 1993 to hndle mnure from the 1500-hed reserch beef feedlot nd the 150-cow diry t the University of Nebrsk Agriculturl Reserch nd Development Center ner Med, Neb. Since then, compost s wste mngement system hs been evluted by determining costs of composting, costs of spreding, nutrient recoveries during composting nd yield impcts from compost mendment to soil. Reserch progress reports hve been provided in previous beef reports (1996 Nebrsk Beef Report, pp ; 1997 Nebrsk Beef Report, pp ). However, until this pst yer, sufficient repliction for detiled summries of crop yield impcts from compost mendment were unvilble. Yield differences from tretments were evluted using both incresed revenue nd cost of tretments. Corn price ws bsed on Nebrsk Agriculturl Sttistics Service for mrketing yers from 1992 to 1998 or $2.50 per bushel. The soyben price ws lso bsed on Nebrsk Agriculturl Sttistics Service for mrketing yers from 1992 to 1998 which is $6.05 per bushel. Composting ws done in windrows during the summer months (My to October) nd ws dependent on mnure supply nd timing. Once windrows were formed, smples were collected from rndom loctions. Compost ws considered finished when windrows no longer produced het two to seven dys fter turning. Diry mnure ws mended t the time of windrow formtion with orgnic residue tht vried from yer to yer. In 1998 nd 1999, feedlot compost ws mended with orgnic residue to increse crbon content nd the C:N (crbon:nitrogen) rtios. After complete composting, windrows were gin smpled. Smples were composited by time nd by windrow nd nlyzed for DM, OM, N (nitrogen), P (phosphorus), K (potssium), nd most minerl elements. Nitrogen recoveries were clculted using totl sh s n internl mrker nd the following eqution: Nitrogen recovery = 100 x [ (% sh before % sh fter) x (% N fter % N before)]. Ash nd N concentrtions re on DM-bsis. Since 1993, pproximtely 1100 cres hve received compost through this reserch project. Check strips, where no compost ws pplied, hve been mintined in lrge-scle production fields by GPS/GIS technology to ensure strip identity nd integrity. Yield dt hve been collected nd summrized for compost produced from 1993 to Until 1997, compost ppliction ws trgeted t 10 tons (s-is) per cre. In 1998 nd 1999, compost ppliction ws incresed to 20 tons (s-is) per cre. Fields were chosen bsed on Bry-P1 soil phosphorus test less thn 15 ppm s the criticl soil test vlue, nd the vilbility of compost. Yields were determined by collection of totl weight from check strips (Figure 1) by using 550 bu Brent (model 672) grin crt equipped with J-str lod cells, or by truck scle. When weighing cpbility ws unvilble, yields were determined by clibrted yield monitors (Agleder PF3000) from grin combines. Most of the corn yields nd 50% of soyben yields were determined with weights from the grin crt, with the remining soyben yields determined using yield monitors. Fields were 2001 Nebrsk Beef Report Pge 92

93 No compost check strip Compost check strip Border rows Received None Received compost pplied compost on either n irrigted, no-till cornsoyben rottion or non-irrigted, no-till corn-soyben rottion. Some dt were collected on non-irrigted, no-till whet nd grin sorghum crops. Dt were nlyzed within ech crop by yer from ppliction time, i.e. whether one, two, three nd four or more yers from compost mendment, using proc GLM in SAS. Results Compost production Figure 1. Digrmmtic representtion of check strips for yield comprisons between compost tretment versus no compost tretment. Ech strip represents n 8-row (20 foot) width which mtches plnting nd hrvest equipment. Tble 1. Compost nutrient composition nd tonnge for 1993 to The yer represents the summer tht composting occurred. Feedlot compost Lb per ton of DM Tons(s-is) DM, % N P N recovery verge Diry compost Lb per ton of DM Tons(s-is) DM, % N P verge mnged similrly in terms of crop, vriety or hybrid, irrigtion, N fertiliztion nd plnting/hrvesting dtes. No commercil P ws pplied. To ccount for vrition from field to field, field nd compost tretment were included in the yield model. Most fields (mjority of the dt) were mintined Nitrogen concentrtion is usully n indictor of compost qulity nd soil contmintion. In 1993 nd 1998, feedlot compost ws lower in qulity (Tble 1). Those yers were ssocited with unusully wet springs nd therefore pens were clened nd more soil unvoidbly removed. Totl tonnge ws lso reltively high those yers which is further evidence tht more soil ws removed. Animl cpcity ws unchnged nd therefore more mnure would not be ssocited with niml production. Averging cross the seven yers, the 1500-hed feedlot produced n verge of 1,155 tons (s-is) nnully of finished compost tht contined 12.9 lb of N nd 9.4 lb of P per ton of DM. Dry mtter concentrtion verged 78.8%. Therefore, 10.2 lb of N nd 7.4 lb of P were produced per ton of s-is compost. Converting P to P 2 O 5 bsis leds to 16.9 lb of P 2 O 5 per ton of s-is compost from the feedlot. Using the verge N concentrtion of 10.2 lb, the vlue of N is $1.14 per ton (s-is) ssuming N is priced t $0.112 per lb (NH 3 = $185 per ton equivlent, bsed on 2000 prices). Similr clcultions for P suggests tht the vlue of P is $4.97 per ton (s-is) ssuming $0.294 per lb of P 2 O 5 ( = $330 per ton equivlent). Diry compost ws reltively consistent cross yers nd ws generlly higher qulity bsed on N concentrtion due to mnure production nd hndling differences reltive to feedlot mnure. Diry mnure ws huled fresh to the compost yrd dily, nd stored. Differences exist between fresh diry mnure nd feedlot mnure; however, mnure (Continued on next pge) Pge Nebrsk Beef Report

94 collected fresh from feedlot nimls would produce compost similr to diry compost rther thn typicl feedlot compost from mnure collected on open-dirt pens. In the summer, mnure ws plced in windrows nd mixed with orgnic residue. As result, soil contmintion ws much lower nd compost tonnge ws more constnt. Beginning in 1999, less mnure ws huled to the compost yrd due to direct pplictions of fresh diry mnure on other ARDC cres. Averged cross the seven yers, the 150-cow diry produced 1,360 tons (s-is) nnully of finished compost tht contined 17.6 lb of N nd 12.0 lb of P per ton of DM. Dry mtter concentrtion verged 71.9%. Therefore, 12.6 lb of N nd 8.6 lb of P were produced per ton of s-is compost. Converting P to P 2 O 5 bsis leds to 19.8 lb of P 2 O 5 per ton of s-is compost from the diry. Using the verge N concentrtion of 12.6 lb, the vlue of N is $1.41 per ton (s-is) ssuming N is priced t $0.112 per lb. Similr clcultions for P suggests tht the vlue of P is $5.82 per ton (s-is) ssuming $0.294 per lb of P 2 O 5. During composting, energy is required in the form of crbon (orgnic mtter) to mximize N recovery. Therefore, criticl mesure in mnure is the crbon to nitrogen (C:N) rtio. Tht rtio in feedlot mnure is usully 12:1 wheres optiml C:N rtios re 25:1 or greter. The consequences of low C:N rtios re greter N losses. Tble 1 contins N recovery rnges for feedlot compost in these studies. N recovery is vrible but rnges from 60 to 90%, which suggests tht the mjority of N is trnsformed from inorgnic N to orgnic N. Once pplied, orgnic N should be more stble thn tht in mnure nd eventully be used by the growing crops. Crop yields Adding compost to irrigted cres improved (P <.10) corn yields in the first nd second yers following ppliction (Tble 2). Yields were incresed by 8.9 bushels, which ws 6% the first yer nd by 3.8 bushels or 2.5% the second yer. Ten fields were plnted with corn those two yers. After the second yer, compost tretment hd no impct (P >.25) on Tble 2. Yield responses (bu/cre) from compost tretment on irrigted nd drylnd corn. Yers -comp +comp diff (bu) diff (%) fields SE P= Irrigted overll vg Drylnd overll vg Yers is the number of yers following one-time compost ppliction, -comp is tretment not receiving compost, +comp is tretment receiving compost, differences in bushels nd percentge clculted s +comp minus -comp divided by -comp tretment, fields is mesure of repliction, SE is the stndrd error of the men, nd P= is the probbility tht the +comp nd -comp tretments re equl when vrition due to fields is ccounted for. Tble 3. Yield responses (bu/cre) from compost tretment on irrigted nd drylnd soybens. Yers -comp +comp diff (bu) diff (%) fields SE P= Irrigted overll vg Drylnd overll vg Yers is the number of yers following one-time compost ppliction, -comp is tretment not receiving compost, +comp is tretment receiving compost, differences in bushels nd percentge clculted s +comp minus -comp divided by -comp tretment, fields is mesure of repliction, SE is the stndrd error of the men, nd P= is the probbility tht the +comp nd -comp tretments re equl when vrition due to fields is ccounted for. corn yield. Assuming 3.6 bushel increse in corn yield ech yer for four yers (bsed on overll verge response), then compost tretment increses gross returns by $36 per cre if verge price for corn is $2.50 per bushel for those four yers (3.6 bushels x 4 yers x $2.50 per bushel). If ppliction costs verge $2.50 per ton (bsed on previous clcultions; 1997 Nebrsk Beef Report, pp ), then totl spreding costs re $25 per cre for 10 tons per cre ppliction rtes or $50 if 20 tons per cre re pplied. Appliction costs re vrible nd dependent on size of opertion nd distnce trveled. We used n verge, but individul producers would need to ssess their ppliction costs. Most of the yield dt presented here follows n ppliction rte of 10 tons per cre (five of the six yers). In these clcultions, only four yers were used in the economic clcultions to obtin conservtive estimtes, wheres some of these fields received compost six yers erlier. Therefore, totl income would be incresed by pproximtely $11 per cre if compost is used on irrigted corn ground. Adding compost to non-irrigted corn cres incresed (P <.04) yields by 10 bushels or 8% the first yer fter ppliction. In subsequent yers, the impct of dding compost ws not sttisticlly significnt except for the fourth yer fter compost ppliction. Bsed on the results in Tble 2, compost 2001 Nebrsk Beef Report Pge 94

95 Tble 4. Crop yield responses (bu/cre) from compost tretment on drylnd whet nd grin sorghum yields. Yers -comp +comp diff (bu) diff (%) fields SE P= Whet Grin sorghum 1,3, Yers is the number of yers following one-time compost ppliction, -comp is tretment not receiving compost, +comp is tretment receiving compost, differences in bushels nd percentge clculted s +comp minus -comp divided by -comp tretment, fields is mesure of repliction, SE is the stndrd error of the men, nd P= is the probbility tht the +comp nd -comp tretments re equl when vrition due to fields is ccounted for. tretment numericlly incresed drylnd corn yields in every yer mesured (up to six yers); however, vrition from yer to yer ws probbly due to precipittion differences. With vrible yields due to wether effects during different yers, effects due to compost ppliction were not distinguishble. Biologiclly, 1 to 2 percent improvement in yields observed during the second to fourth yer is significnt. If yield is incresed 3.4 bushels due to compost tretment, then gross income is incresed by $34 (3.4 bushels x 4 yers x $2.50 per bushel). With similr clcultions s in the irrigted corn exmple, net income would be incresed by pproximtely $9 per cre if compost is pplied t rte of 10 tons per cre to drylnd corn. When soybens were plnted on irrigted cres, compost tretment incresed (P <.06) yields by 1.3 bushels or 2.2% the first yer (Tble 3). In subsequent yers, compost tretment did not sttisticlly increse yields (P >.32). Yield improvements decresed linerly with yer from ppliction bsed on percent improvements from 2.2% (yer 1) to 0.2% (yers 4 nd 5). Performing similr economic clcultions with the soybens s with the corn nd n verge yield improvement of 0.9 bushels, pplying compost dded bout $21.50 return per cre (0.9 bushels x 4 yers x $6.05). The differences in yield lone from compost ppliction to irrigted soybens does not offset the verge ppliction costs ($25) in this study. Becuse soyben yields re lower thn those of corn in bushels per cre (60 versus 168), yield differences re more difficult to ssess. With non-irrigted soybens, compost tretment did not result in sttisticl differences in yield (Tble 3) when compred with the no-compost tretment. During ech yer from ppliction, yields were incresed by compost ppliction. The overll verge increse bove the no-compost tretment ws 1.2% or 0.6 bushels. Only three fields were used to mesure drylnd soyben yields in the first nd second yers following ppliction. These fields were plnted to other crops, either corn, whet, or grin sorghum. If more observtions were vilble, then the numericl differences my be significnt. Bsed on the stndrd errors, vrition in yields on drylnd soybens is greter thn vrition in yields from irrigted cres. The incresed vrition in drylnd situtions is presumbly relted to precipittion differences nd the subsequent impct tht wether hs on yields. This trend is similr when corn is grown on drylnd cres (Tble 2). On some of the non-irrigted cres previously discussed, whet ws grown the first yer fter spring ppliction of compost. Whet yield ws influenced more thn ny other crop by compost tretment. Spreding compost on whet cres incresed (P <.04) yield by 12% or 4.4 bushels per cre the first yer fter ppliction (Tble 4). With the whet crop, corn silge ws hrvested in September nd compost pplied just prior to whet plnting. When grin sorghum ws grown on compost-treted cres, yield ws incresed (P <.04) by 2.2 percent or 2.6 bushels compred to the no-compost tretment. The yield response for grin sorghum ws verged cross one, three, nd five yers following the one-time ppliction of compost. In summry, yields were incresed when compost ws pplied to irrigted corn nd soybens, drylnd corn, drylnd whet, nd drylnd grin sorghum. The economic returns were gretest for corn nd covered costs ssocited with spreding. The costs ssocited with composting ($1.50 per ton bsed on 1997 Nebrsk Beef Report, pp ) re not included in the economic returns. However, the vlue of nutrients in compost in this study were lso not included nor were the costs ssocited with disposl of mnure. In this project, N fertiliztion ws not reduced in the compost treted strips. Thus ll the reported increses in yields nd income were over nd bove the yields from crops receiving the recommended N fertilizer rtes bsed on soil tests. There would be some cost svings if N fertiliztion were reduced on compost-treted fields, ssuming compost will provide portion of crop vilble N. Becuse N fertiliztion ws held constnt, we conclude tht the yield response is probbly due to P but other nutrients might hve influenced yield. Whether yield improvements result from dded P, OM, K, or other nutrients is not known, only tht there is benefit from one of these or combintion. 1 Glen Erickson, grdute student, Terry Klopfenstein, Professor, Animl Science, Lincoln; Wlker Luedtke, reserch coordintor, Mrk Schroeder, frm opertions mnger, Agriculturl Reserch nd Development Center, Med; Chuck Frncis, director, Center for Sustinble Agriculturl Systems, Gry Lesoing, former reserch ssistnt professor, Center for Sustinble Agriculturl Systems, Lincoln 2 This mteril is bsed upon work supported by the Coopertive Stte Reserch, Eduction, nd Extension Service, U.S. Dept. of Agriculture, under Agreement No Any opinions, findings, conclusions, or recommendtions expressed in this publiction re those of the uthors nd do not necessrily reflect the view of the USDA. Pge Nebrsk Beef Report

96 Consumer Acceptnce nd Vlue of Strip Steks Differing in Mrbling nd Country-of-Origin K.M. Killinger C.R. Clkins W.J. Umberger D.M. Feuz K.M. Eskridge 1 Consumers found high mrbled beef nd domestic beef more cceptble in pltbility thn low mrbled beef nd Argentine beef nd generlly were willing to py more for more cceptble products. Summry Consumers (72.6%) visully preferred low mrbled steks. However, high mrbled steks were rted more juicy, tender nd desirble in flvor nd overll cceptbility thn low mrbled steks. Bsed on uction bids, consumers in Chicgo (but not Sn Frncisco) were willing to py more for high mrbled steks thn low mrbled steks. Domestic steks were rted higher in ll sensory ttributes thn Argentine steks. Consumers in both loctions were willing to py more for domestic steks thn Argentine steks. Although most consumers visully prefer low mrbled steks, most consumers find high mrbled steks to be more cceptble in sensory chrcteristics. Introduction Current reserch involving the sensory chrcteristics of beef hs focused on consumer cceptnce of beef tenderness nd the vlue consumers plce on tenderness. However, n improvement in beef tenderness lone my not be sufficient to increse overll consumer cceptnce of beef. In this study, fctors ffecting beef flvor were studied to discover the importnce of beef flvor on consumer cceptnce nd the vlue consumers plce on flvor. Mrbling hs been used in the met industry s visul indictor of beef pltbility; therefore, strip loins differing in mrbling level, but similr in tenderness, were used to investigte the effect of mrbling on consumer cceptnce. In ddition, Argentine beef hs been sid to hve unique flvor (due to grss feeding nd longer ging periods), so Argentine nd domestic strip loins, of similr mrbling level nd tenderness, were used to determine consumer cceptnce of beef from Argentin nd the United Sttes. Finlly, experimentl uction procedures were used to determine the vlue consumers plced on beef tht differed in mrbling level nd country-of-origin. Procedure Selection of Strip Loins Strip loins of two qulity grdes (Select nd Upper 2/3 Choice) nd of two countries (United Sttes nd Argentin) were purchsed nd shipped to the University of Nebrsk-Loeffel Met Lbortory. Ech strip loin ws ssigned rndom, three-digit code. The strip loins were ged for nine dys t 32 o F, nd subsequently frozen. The strip loins were lter cut into steks, nd the steks were lbeled in scending order from nterior to posterior. Stek 1 (the most nterior stek) ws used for n objective tenderness determintion, nd stek 2 ws held in reserve. Thwed steks were cooked on tble-top broiler to n internl temperture of 160 o F. The steks were llowed to cool prior to coring with n utomted coring device. Cores (1/2 inch dimeter) were then shered to determine Wrner-Brztler sher force using n Instron Universl Testing Mchine. For the mrbling comprison, high mrbled (upper 2/3 Choice) nd low mrbled (Select) strip loins with similr (P>0.05) Wrner-Brtzler sher force vlues were pired for sensory evlution, while steks for the countryof-origin comprison were pired bsed on similr (P>0.05) Wrner-Brztler sher force vlues nd similr (P>0.05) mrbling scores. In the country-oforigin comprison, ll pirs were within the Select qulity grde. Aging of Argentine beef ws not under experimentl control, nd the exct ging period ws unknown. However, informtion provided by the Argentine supplier indictes tht the beef ws ged for t lest 30 dys which ssures tht the Argentine beef ws ged for longer period thn the domestic beef (nine dys). Therefore, time of ging my contribute to the unique flvor of the Argentine beef used in this study. Efforts to minimize vrition due to tenderness within ech pir for the mrbling comprison nd to minimize vrition due to both tenderness nd mrbling within ech pir for the country-oforigin comprison dd to the uniqueness of the study. Selection of consumers Consumers in two loctions (Chicgo nd Sn Frncisco) were screened over the telephone in order to qulify for the study. To be eligible, consumers hd to meet three criteri. They hd to be between the ges of 19 nd 59, be the primry grocery shopper of the household nd be willing to consume beef. In ddition to these requirements, efforts were mde to blnce the selected consumers in regrd to ge, level of beef consumption, gender, economic ctegory, nd ethnicity. In ech city, 12 pnels were scheduled over three-dy period with trget of 12 consumers per pnel. Tste pnel procedures Prior to the tste pnels, selected consumers were miled consent form nd survey to discern the consumer s 2001 Nebrsk Beef Report Pge 96

97 Percent eting preferences, met purchsing behviors nd other demogrphic chrcteristics. The consumers brought these forms with them nd were pid for their prticiption upon rrivl ($25 in Chicgo nd $35 in Sn Frncisco). Consumers were compensted with mounts comprble to other test mrketing fcilities in the respective cities. Next, consumers were sked to visully evlute pir of steks in retil disply cse. Steks of different mrbling level (upper 2/3 Choice nd Select) were purchsed t locl retil stores in ech loction. The steks were pckged similrly nd were lbeled with four-digit rndom number codes. Consumers were sked to choose the stek tht they would purchse if shopping in grocery store, list the selection criteri they used to choose the stek nd provide the price tht they were willing to py for ech stek. Then, the experimentl uction procedures were explined. Consumers were informed tht in ech uction they would be bidding for one-pound pckge (consisting of two frozen steks) from the sme strip loins s the smples in the tste pnels. In ech uction, there would be three winners, ech receiving onepound pckge of stek. The uction method used ws Vickery uction, which is silent, seled-bid uction. Two prctice uctions were conducted Figure 1. Percentge of selection criteri listed by ech preference group Mrbling Ft Appernce Color Cooked Qulity Preferred High Mrbling Preferred Low Mrbling using the visul evlution steks. The consumers then evluted wrm-up stek smple nd third prctice uction ws conducted. The prctice uctions were simply used to cquint the consumers with the uction procedures; the products used in these uctions were not purchsed by the winning bidders. Tste pnel smple preprtion Pired strip loins were rndomly ssigned to tste pnels. For the mrbling comprison, ech tste pnel ws ssigned two mtched pirs nd for the country-of-origin comprison, one mtched pir ws ssigned. Frozen steks were shipped to the tste pnel fcilities. Steks 3, 4 nd 5 from ech strip loin were used for tste pnel smples. These steks were thwed t refrigertion tempertures for bout 24 hours prior to cooking. The steks were then cooked to 160 o F nd cut into smll rectngles for sensory evlution. Steks 6-11 remined frozen nd were used in the uctions. Consumers used n eight-point hedonic scle to rte tste pnel smples for juiciness (1=extremely dry, 8=extremely juicy), tenderness (1= extremely tough, 8=extremely tender), flvor nd overll cceptbility (1= extremely undesirble, 8=extremely desirble). After evluting ech pir of smples, consumers hd the opportunity to prticipte in n uction for steks from the sme strip loin s the smples they tsted. This procedure ws performed three times (two mrbling comprisons nd one country-of-origin comprison). Sttisticl nlysis Consumers in experimentl uctions tend to bid mounts tht do not reflect the mrket vlue of the products. Using Vickery uction, insted of focusing on the bsolute bids for the products differing in mrbling or country-oforigin, the nlysis focuses on the differentil between the two bids, which better reflects the vlue consumers plce on the products. Price dt were nlyzed using the mixed procedure of SAS nd visul preference dt were nlyzed using the chi squre procedure in SAS. Results In regrd to pnel demogrphics, totl of 248 consumers prticipted in the study (124 in ech loction). In Chicgo, the pnels consisted of 102 femles nd 22 mles, while in Sn Frncisco, 96 femles nd 28 mles prticipted. In both loctions, most consumers were between the ges of 30 nd 59, nd consumed beef 1-4 or more times per week. Their yerly incomes rnged from $10, ,000 or more/ yer. Most of the consumers were Cucsins. There ws significnt difference in visul preference with 72.6% of consumers preferring the low mrbled stek. Selection criteri were ctegorized into five min ctegories: mrbling, ft, color, ppernce nd cooked qulity (Figure 1). A mjority of consumers (61.6%) who preferred low mrbling listed ft s selection criteri, while mjority of consumers (65.4%) who preferred high mrbling listed mrbling s selection criteri. It ppers tht visul preference for steks differing in mrbling is influenced by consumer perception of mrbling s negtive fctor (high ft content) or positive fctor (increses flvor nd juiciness). (Continued on next pge) Pge Nebrsk Beef Report

98 In regrd to price, there ws significnt interction between visul preference nd mrbling level. Consumers who preferred the high mrbled stek were willing to py $0.75/lb more (P<0.01) for the high mrbled stek (Tble 1). Consumers who preferred the low mrbled stek were willing to py $1.12/lb more (P<0.01) for the low mrbled stek. Consumers plced higher vlue on the stek (high or low mrbled) tht they preferred, bsed on visul ssessment. It ppers tht consumers who re concerned bout ft content plce higher vlue on low mrbled steks thn consumers who wnt to purchse stek with high eting qulity plce on high mrbled steks. In the tste pnel evlutions, consumers rted high mrbled steks more (P<0.01) desirble in flvor s well s more (P<0.01) juicy nd more (P<0.05) tender (Tble 2). Although pirs were mtched bsed on Wrner-Brtzler sher force vlues, consumers perceived differences in tenderness. It is not surprising tht objective nd subjective evlutions of tenderness re different. Finlly, consumers rted high mrbled steks s being more (P<0.01) desirble overll. Consumers in Chicgo were willing to py $0.23 more (P<0.05) for high mrbled steks thn low mrbled steks (Tble 3), while consumers in Sn Frncisco were only willing to py $0.09 more (P>0.05) for high mrbled steks thn low mrbled steks. Consumers in both loctions rted high mrbled steks higher in ll sensory ttributes; however, only consumers in Chicgo were willing to py significntly more for the high mrbled steks, bsed upon pltbility chrcteristics. There re likely vriety of resons tht consumers in Chicgo nd Sn Frncisco vlued high nd low mrbled beef differently. Even so, mrbling is clerly n importnt fctor tht ffects beef pltbility. Consumers need to be wre of the importnce of mrbling, nd tht they re likely to find high mrbled steks more cceptble thn low mrbled steks. Consumers found the domestic steks to be more (P<0.01) desirble in flvor nd rted domestic steks higher (P<0.01) in juiciness, tenderness nd overll cceptbility (Tble 4). Consum- Tble 1. The vlue consumers plce on steks differing in mrbling level bsed on visul evlution ($/lb). Price for high Price for low Differentil P-Vlue mrbled stek mrbled stek Preferred high mrbling $3.77 $3.02 $0.75 <0.01 Preferred low mrbling $2.98 $4.10 $1.12 <0.01 Tble 2. Tste pnel rtings for high nd low mrbled steks. Attribute High mrbled steks Low mrbled steks P-vlue Flvor rting <0.01 Juiciness rting <0.01 Tenderness rting <0.05 Overll cceptbility rting <0.01 Smples rted using n 8-point hedonic scle (8=extremely desirble, juicy, tender, desirble; 1=extremely undesirble, dry, tough, undesirble). Tble 3. The vlue consumers plce on high nd low mrbled steks bsed on experimentl uction bids ($/lb). High mrbled Low mrbled Differentil P-vlue stek bid stek bid Chicgo $2.38 $2.16 $0.23 <0.05 Sn Frncisco $2.70 $2.61 $0.09 >0.05 Tble 4. Tste pnel rtings for Argentine nd domestic steks. Attribute Domestic steks Argentine steks P-vlue Flvor rting <0.01 Juiciness rting <0.01 Tenderness rting <0.01 Overll cceptbility rting <0.01 Smples rted using n 8-point hedonic scle (8=extremely desirble, juicy, tender, desirble; 1=extremely undesirble, dry, tough, undesirble). Tble 5. The vlue consumers plce on domestic nd Argentine steks bsed on experimentl uction bids ($/lb). Domestic Argentine Differentil P-Vlue stek bid stek bid Chicgo $2.63 $1.74 $0.89 <0.01 Sn Frncisco $2.59 $2.10 $0.48 <0.01 ers in Chicgo were willing to py $0.89 more (P<0.01) for domestic steks thn Argentine steks, nd consumers in Sn Frncisco were willing to py $0.48 more (P<0.01) for domestic steks thn Argentine steks (Tble 5). The Argentine beef used in this study ws imported from supplier tht used grss-fed cttle nd long ging period. Grss-fed beef tends to hve different flvor profile thn grin-fed beef, which is more typicl of commercil beef in the United Sttes. Length of ging lso will ffect the flvor of beef, nd the Argentine beef ws ged longer thn most beef in the United Sttes. With both of these fctors contributing to the flvor of the Argentine beef, it is not surprising tht consumers found substntil difference in flvor between the two products. While the flvor of Argentine beef my be unique, the consumers in this study found domestic beef to be more cceptble nd plced higher vlue on domestic beef. 1 K.M. Killinger nd W.J. Umberger, grdute students, C.R. Clkins, professor Animl Science, Lincoln, K.M. Eskridge, professor, Biometry, Lincoln, D.M. Feuz, ssistnt professor, Agriculture Economics, Pnhndle Reserch nd Extension Center, Scottsbluff. This project ws funded by beef producers through their $1/hed checkoff nd produced for the Cttlemen s Beef Bord nd Stte Beef Councils Nebrsk Beef Report Pge 98

99 Physicl nd Chemicl Properties of 39 Muscles from the Beef Chuck nd Round Drew D. Von Seggern Chris Clkins 1 Vrition mong the muscles of the beef chuck nd round re profound. Physicl nd chemicl properties of these muscles were shown to be ffected the most by qulity grde. Summry Twenty-seven nd 12 muscles, respectively, from the chuck nd round were nlyzed for objective color, expressible moisture, emulsion cpcity, ph, totl collgen content totl heme-iron content, nd proximte composition. Observtions of these physicl nd chemicl properties showed vst rnge of results. The rnge in dt revel the vrition within nd mong muscles. Knowledge of this vrition cn led to proper usge, thereby incresing vlue of the beef chuck nd round. Qulity grde hd the most pronounced effects, wheres yield grde nd weight showed fewer effects on these trits cross ll 39 muscles. Introduction With the incresing populrity of vlue-dded products nd the decline in vlue of the beef chuck nd round (20-25% over five-yer period), it s necessry to chrcterize the muscles from these two primls. Muscle hs unique physicl nd chemicl properties, which when known nd understood cn llow for development of vluedded products. Informtion (physicl nd chemicl properties) of mny muscles within the chuck nd round ws lcking until this study ws undertken. It is lso importnt to describe the effects of qulity grde, yield grde, nd weight of crcss on these properties. Therefore, the objectives of this study were to determine the physicl nd chemicl properties of 39 muscles from the beef chuck nd round nd the effects of qulity grde, yield grde, nd weight on these properties. Procedure Ninety-four chucks nd 94 rounds were selected t the IBP Inc., Dkot City, Neb. plnt bsed on qulity grde (upper 2/3 Choice, low Choice, nd Select), yield grde (1, 2, 3, nd 4 nd 5 together), nd crcss weight ( lb nd lb). Twenty-seven nd 12 muscles, respectively, were dissected from chucks nd rounds. Ech individul muscle ws then trimmed of ll externl ft nd connective tissue. Objective color (L*, *, nd b* vlues) ws observed using Hunter Lb Mini Scn device with 1- inch port. Expressible moisture, method of mesuring wter holding cpcity, ws mesured s the percentge of moisture lost due to centrifugtion. Muscle ph ws determined using ph meter with sper tip combintion electrode. Emulsion cpcity, which determines the mount of oil specific muscle/protein system cn bind, ws expressed s ml oil bound/2.5g of len tissue. Totl collgen mesures the mount of connective tissue within given muscle. It ws quntified by mesuring the totl content of hydroxyproline in smple, which is relted to collgen. Totl collgen ws expressed s mg of collgen/g of len tissue. Totl heme-iron mesures the mount of myoglobin nd hemoglobin within given muscle. Acetone nd hydrochloric cid were used to seprte myoglobin nd hemoglobin from the smple. This solution then ws red using spectrophotometer; results were expressed in prts per million (ppm). Proximte composition (ft, moisture nd sh) ws determined using Soxhlet ether extrction procedures nd LECO Thermogrvimetric Anlyzer ( continuous weighing nd heting device). Ft, moisture nd sh were expressed s mg/g (%) of len tissue. Dt were nlyzed sttisticlly using mixed nd lest squre mens procedures. Results Across ll 39 muscles, vrition ws evident in ll nlyzed physicl nd chemicl properties (Tbles 1-4). Objective color (L*, *, nd b*) vlues represent color scle. The higher the L* (rnging from 0 = blck to 100 = white), the lighter the muscle. As * (rnging from negtive 60 = green to positive 60 = red) increses, the muscle becomes more red. As b* (rnging from negtive 60 = blue to positive 60 = yellow) increses, the muscle becomes more yellow. The overll mens nd stndrd devitions observed for L*, *, nd b* were , , nd , respectively. The mesurement of objective color cn be correlted to other chemicl properties such s ph nd totl heme-iron, which together cn be relted to the shelf-life of specific muscle nd the ultimte color of processed product. (Continued on next pge) Pge Nebrsk Beef Report

100 Tble 1. Properties of chuck muscles. Emulsion cpcity Expressible (ml oil/2.5g) Moisture (%) L* - vlue * - vlue b* - vlue Muscle Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Biceps brchii (14.7) (4.22) (3.56) (3.75) (4.32) Brchiocephlicus omo-trnsversrius (18.1) (5.95) (2.70) (3.27) (3.34) Brchilis (20.6) (5.41) (4.03) (3.74) (4.28) Cutneous omo-brchilis (27.3) (8.17) (5.63) (4.54) (4.45) Complexus (17.1) (5.31) (2.47) (3.00) (3.56) Deltoideus (15.1) (4.62) (3.68) (3.33) (3.39) Deep pectorl (20.6) (4.57) (3.08) (3.23) (3.52) Dorslis oblique (19.3) (4.52) (2.64) (3.34) (3.72) Infrspintus (15.0) (4.70) (2.60) (3.08) (3.64) Intertrnsversles (14.9) (5.24) (4.04) (3.17) (3.71) Ltissimus dorsi (19.6) (5.15) (3.50) (4.03) (4.35) Longissimus cpitus et Atlntis (14.9) (5.31) (3.83) (4.17) (4.57) Longissimus costrum (18.3) (5.90) (4.31) (3.77) (3.84) Longissimus dorsi (16.8) (4.27) (3.03) (3.46) (4.00) Levtores costrum (19.7) (5.28) (3.87) (3.62) (3.88) Multifidus/Spinlis dorsi (17.0) (5.47) (3.34) (3.87) (4.94) Rhomboideus (16.2) (4.77) (3.04) (3.48) (3.90) Sclenus dorslis (19.7) (4.73) (3.67) (3.72) (3.92) Serrtus ventrlis (16.4) (5.72) (2.98) (2.87) (3.49) Splenius (19.6) (6.53) (2.88) (3.78) (4.19) Superficil pectorl (15.9) (5.52) (3.75) (3.06) (3.07) Subscpulris (14.4) (4.64) (4.09) (2.86) (3.46) Suprspintus (17.9) (4.95) (3.35) (3.03) (3.51) Teres mjor (24.1) (4.83) (3.75) (3.74) (4.21) Tensor fsci ntibrchii (17.8) (4.73) (3.17) (3.86) (4.11) Trpezius (25.0) (5.07) (4.69) (4.64) (5.41) Triceps brchii (19.7) (20.20) (2.80) (3.62) (4.38) Tble 2. Properties of chuck muscles. Totl Collgen Heme Iron Ft Moisture Ash (mg/g) (ppm) ph (mg/g) (mg/g) (mg/g) Muscle Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Biceps brchii (7.32) (2.88) 5.79 (0.33) 6.79 (2.17) (1.66) 1.07 (0.19) Brchiocephlicus omo-trnsversrius (6.48) (3.12) 5.75 (0.31) 6.40 (2.14) (1.47) 1.14 (0.18) Brchilis (4.36) (2.85) 5.76 (0.30) 4.04 (1.23) (1.19) 1.43 (0.22) Cutneous omo-brchilis (5.68) (6.47) 5.81 (0.32) (4.19) (6.70) 1.04 (0.19) Complexus (4.68) (2.13) 5.76 (0.33) 8.37 (1.88) (1.48) 1.48 (0.08) Deltoideus (8.13) (2.09) 5.77 (0.33) 6.45 (1.75) (1.71) 1.23 (0.17) Deep pectorl (4.67) (3.25) 5.73 (0.32) 5.49 (1.93) (1.32) 1.41 (0.23) Dorslis oblique (3.84) (2.18) 5.88 (0.37) 9.07 (2.32) (1.89) 1.12 (0.18) Infrspintus 8.72 (3.33) (2.87) 5.78 (0.32) 9.18 (2.54) (2.05) 1.08 (0.11) Intertrnsversles (5.55) (2.92) 5.77 (0.34) 8.56 (2.45) (1.96) 1.03 (0.14) Ltissimus dorsi (7.67) (2.94) 5.74 (0.32) 5.99 (1.51) (1.41) 1.23 (0.16) Longissimus cpitus et Atlntis (7.62) (3.83) 5.79 (0.32) 6.49 (1.92) (1.37) 1.07 (0.12) Longissimus costrum (8.19) (3.40) 5.86 (0.33) (3.48) (2.75) 1.08 (0.20) Longissimus dorsi (9.07) (4.48) 5.71 (0.27) 7.74 (1.95) (1.58) 1.20 (0.14) Levtores costrum 8.87 (4.40) (1.96) 5.86 (0.32) 9.86 (2.45) (1.95) 1.09 (0.17) Multifidus/Spinlis dorsi (11.71) (2.45) 5.80 (0.41) (2.67) (2.11) 1.01 (0.21) Rhomboideus (5.09) (3.45) 5.82 (0.32) 6.35 (1.93) (1.43) 1.38 (0.15) Sclenus dorslis (4.26) (1.99) 5.75 (0.34) 9.11 (3.11) (2.53) 0.98 (0.18) Serrtus ventrlis 8.78 (3.82) (3.13) 5.81 (0.28) (3.05) (2.43) 1.02 (0.11) Splenius (9.16) (3.18) 5.71 (0.29) 4.35 (1.44) (1.39) 1.33 (0.24) Superficil pectorl 8.21 (4.90) (4.97) 5.77 (0.27) (2.90) (2.29) 1.10 (0.09) Subscpulris (6.11) (2.39) 5.85 (0.33) 4.60 (1.26) (1.19) 1.31 (0.20) Suprspintus (11.00) (3.25) 5.82 (0.32) 4.95 (1.08) (0.95) 1.37 (0.15) Teres mjor (3.74) (2.33) 5.72 (0.34) 5.25 (1.29) (1.11) 1.23 (0.31) Tensor fsci ntibrchii 9.95 (5.36) (2.91) 5.79 (0.37) 4.57 (1.36) (1.16) 1.24 (0.15) Trpezius 8.85 (4.90) (3.19) 5.82 (0.33) 8.65 (1.91) (2.06) 0.93 (0.11) Triceps brchii 9.97 (3.84) (2.43) 5.78 (0.38) 5.65 (1.55) (1.27) 1.44 (0.17) 2001 Nebrsk Beef Report Pge 100

101 Tble 3. Properties of round muscles. Emulsion cpcity Expressible (ml oil/2.5g) Moisture (%) L* - vlue * - vlue b* - vlue Muscles Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Adductor (17.9) (4.41) (4.08) (3.71) (3.00) Biceps femoris (16.5) (6.09) (2.78) (2.61) (2.62) Gluteus medius (21.2) (4.72) (3.55) (4.42) (3.14) Grcilis (18.8) (4.99) (2.92) (3.05) (3.54) Pectineus (18.8) (5.20) (4.54) (2.14) (2.51) Rectus femoris (19.5) (4.89) (3.01) (3.32) (2.38) Srtorius (20.0) (4.66) (3.07) (3.13) (3.15) Semimembrnosus (23.7) (4.48) (2.96) (2.53) (2.57) Semitendinosus (17.1) (4.11) (3.11) (2.23) (2.11) Vstus intermedius (20.4) (5.09) (2.99) (1.81) (2.27) Vstus lterlis (16.1) (4.24) (2.75) (2.35) (2.70) Vstus medilis (12.8) (4.23) (3.53) (2.65) (3.51) Tble 4. Properties of round muscles. Totl Collgen Heme Iron Ft Moisture Ash (mg/g) (ppm) ph (mg/g) (mg/g) (mg/g) Muscles Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Men (s.d.) Adductor (11.89) (2.70) 5.76 (0.30) 4.57 (1.21) (0.87) 1.49 (0.23) Biceps femoris (8.32) (3.48) 1.69 (0.30) 6.86 (1.65) (1.29) 1.29 (0.17) Gluteus medius (5.77) (2.57) 5.76 (0.34) 5.94 (1.69) (1.51) 1.40 (0.16) Grcilis (7.92) (4.22) 5.76 (0.31) 3.93 (1.24) (1.06) 1.51 (0.17) Pectineus (6.71) (2.64) 5.84 (0.30) 3.16 (0.83) (0.83) 1.56 (0.18) Rectus femoris (4.23) (3.10) 5.72 (0.32) 5.11 (1.79) (1.22) 1.50 (0.17) Srtorius (3.39) (2.87) 5.75 (0.30) 3.14 (1.29) (1.11) 1.54 (0.27) Semimembrnosus (4.91) (3.29) 5.74 (0.31) 4.36 (1.24) (0.78) 1.75 (0.26) Semitendinosus (6.20) (2.16) 5.72 (0.30) 4.08 (0.90) (0.77) 1.53 (0.15) Vstus intermedius 9.89 (3.46) (2.92) 5.87 (0.40) 8.43 (2.56) (1.77) 0.98 (0.11) Vstus lterlis (5.39) (3.18) 5.77 (0.30) 4.44 (1.15) (0.97) 1.53 (0.26) Vstus medilis (8.75) (3.58) 5.78 (0.28) 4.35 (1.27) (1.14) 1.47 (0.33) The men nd stndrd devition for expressible moisture ws observed to be %. Expressible moisture (long with ph) cn revel good understnding of protein functionlity. Knowledge of the mount of moisture lost due to centrifugtion llows product developers to use technologies to minimize the loss of moisture (loss of yield nd pltbility). The men nd stndrd devition of ph ws observed to be Muscle ph s previously mentioned revels better understnding of protein functionlity. As muscle ph increses, expressible moisture decreses. However, higher ph met ppers to be drker in color (lower L* vlues) nd lso tends to hve shorter shelf-life. The men nd stndrd devition for emulsion cpcity were observed to be ml oil bound/2.5 g of len tissue. This property of muscle cn lso chrcterize specific muscle, s higher mounts of oil bound in protein system cn be relted to the mount of sltsoluble protein (mjor binding protein) within tht system. Such informtion cn llow for incresed yield nd therefore incresed profit in the production of susge-type products. The men nd stndrd devition of totl collgen ws mg/g of len tissue. This property of muscle cn be relted to the tenderness nd texture of met. The men nd stndrd devition for totl heme-iron ws ppm. Totl heme-iron cn revel informtion bout muscle s physicl ppernce (ppernce to the eye), which is mjor fctor in consumer cceptnce. The concentrtion of these color pigments is lso n importnt determinnt of processed met color. Ft, moisture nd sh hd men percentges nd stndrd devitions of , , nd , respectively. To envision the vrition between these 39 muscles, ech muscle ws ctegorized for ech trit into three groups desirble (white), intermedite (gry), or undesirble (blck). These chrts (Tbles 5 nd 6) show specific physicl nd chemicl properties (ft, ph, expressible moisture, emulsion cpcity, totl heme-iron, nd totl collgen) which provide quick, overll picture of prticulr muscles chrcteristics. This cn be useful in selection of cndidte muscles for vlue-dded products. Through investigtion of the effects of qulity grde, yield grde nd weight on the physicl nd chemicl properties, qulity grde ws the effect tht ws most frequently significnt (P <.05). Across ll physicl nd chemicl properties, 2 to 31, 1 to 9, nd 0 to 8 muscles out of 39 showed n effect due to qulity grde, yield grde, nd weight, respectively. For muscles with significnt qulity grde effect, moisture (19 of 23 muscles) nd sh (6 of 15 muscles) decresed while ft (26 of 31 muscles) nd ph (7 of 16 muscles) incresed with n increse in qulity grde. It ws lso observed tht properties showing n increse with n increse in qulity grde were ft (26 out of 31 muscles) nd ph (7 out of 16 muscles). (Continued on next pge) Pge Nebrsk Beef Report

102 Tble 5. Clssifiction of beef chuck muscles by trit. Expressible Emulsion Totl Ft ph Moisture Cpcity Heme-Iron Collgen Biceps brchii Brchiocephlicus omot. Brchilis Cutneous omo brchilis Complexus Deep pectorl Deltoideus Dorslis oblique Infrspintus Intertrnsversles Ltissimus dorsi Longissimus cp. et Atlntis Longissimus costrum Longissimus dorsi Levtores costrum Multifidus nd spinlis dorsi Rhomboideus Sclenus dorslis Serrtus ventrlis Splenius Superficil pectorl Subscpulris Suprspintus Tensor fsci ntibrochii Teres mjor Trpezius Triceps brchii The white cells represent ft <5%, ph >5.8, WHC (expressible moisture) <36%, bind >175 ml, heme-iron >25 ppm, collgen <01 mg/g, while the drk gry cellsrepresent ft >10%, ph <5.7, WHC >38%, bind <170 ml, heme-iron <20 ppm, collgen >15 mg/g. The vlues represented by the light gry cells re intermedite. Tble 6. Clssifiction of beef round muscles by trit. Adductor Biceps femoris Gluteus medius Grcilis Pectineus Rectus femoris Srtorious Semimembrnosus Semitendinosus Vstus intermedius Vstus lterlis Vstus medilis Expressible Emulsion Totl Ft ph Moisture Cpcity Heme-Iron Collgen The white cells represent ft <5%, ph >5.8, WHC (expressible moisture) <36%, bind >175 ml, heme-iron >25 ppm, collgen <01 mg/g, while the drk gry cellsrepresent ft >10%, ph <5.7, WHC >38%, bind <170 ml, heme-iron <20 ppm, collgen >15 mg/g. The vlues represented by the light gry cells re intermedite Nebrsk Beef Report Pge 102

103 Significnt (P <.05) yield grde effects were seldom liner, reflecting inconsistent trends s yield grde incresed or decresed. Moisture (4 out of 5 muscles), L* vlue (7 out of 7 muscles), * vlue (8 out of 8 muscles), b* vlue (6 out of 6 muscles), nd expressible moisture (5 out of 6 muscles) incresed with n increse in weight of crcss. However, ph (4 out of 4 muscles), ft (4 out of 5 muscles), nd emulsion cpcity (5 out 5 muscles) decresed with n increse in weight of crcss. Totl collgen showed no effect cross ll 39 muscles due to weight. These dt indicte vst mount of vrition in physicl nd chemicl properties mong muscles of the beef chuck nd round. Knowledge of these properties now llows individul muscles to be identified nd utilized for production of vlue-dded products. 1 Drew D. Von Seggern, grdute student. Chris Clkins, Professor, Animl Science, Lincoln. This project ws funded by beef producers through their $1/hed checkoff nd produced for the Cttlemen s Beef Bord nd Stte Beef Councils. Fiber Type Composition of the Beef Chuck nd Round Kevin Kirchofer Chris Clkins 1 There is wide vribility in fiber types of beef chuck muscles. This would be expected to crete different processing chrcteristics which influence optiml muscle use in vlue-dded products. Summry The fiber type composition of 38 muscles of the beef chuck nd round ws studied to fcilitte optiml muscle use in vlue-dded products. Select grde chucks nd rounds (n=4 ech) were used. Muscles contining greter thn 40% β-red fiber numbers were clssified s red; greter thn 40% α-white were clssified s white. All others were clssified s intermedite. Nine of 12 round muscles were white, while chuck muscles were eqully dispersed between red (10 of 26), intermedite (9 of 26), nd white (7 of 26), indicting vrition mong muscles of the chuck, which my crete differences in processing chrcteristics. Introduction There is reltionship between ultimte met qulity nd muscle fiber type composition. Muscles with incresed α white (αw) fibers hve more connective tissue, less intrmusculr ft, nd re less tender thn muscles with more β-red (βr) fibers. Not only do individul muscles differ in fiber type composition, but muscle fiber types within specific muscle my be ffected by breed, sex, time on feed nd mturity. Muscle fiber types hve been reported for mny of the lrger muscles of the beef crcss. Little ttention hs been given to the smller muscles tht comprise the chuck nd the round. With mny of these muscles going to further processing, there is need for fiber type profile of these muscles. The objective of this study ws to chrcterize the histochemicl muscle fiber type of 23 muscles of the beef round nd 26 muscles of the beef chuck to help in the ppliction of muscles into vluedded products through the use of further processing. Procedure Select-grde chucks nd rounds (n=4 ech) were chosen representing two weight rnges ( lbs, nd lbs) nd two yield grdes (yield grde 1 nd 3). Twelve muscles of the beef round nd 26 muscles of the beef chuck were fbricted nd smpled. Muscle smples were frozen in liquid nitrogen within nine dys post mortem nd subsequently stored t -112 o F until histochemicl nlysis ws performed. One cubic centimeter of frozen tissue ws mounted on cryostt chuck in such mnner to set muscle fibers perpendiculr to the cutting blde. The mounted cubes were llowed to equilibrte to -4.0 o F before being sliced to thickness of 12 µm on cryostt. The slices were mounted on slides nd llowed to equilibrte to room temperture before being stined. Muscle sections were stined ccording to simultneous stining technique, which included stin for succinic dehydrogense ctivity nd stin for cid-ctive denosine triphosphtse ctivity fter cid incubtion. Cover slips were permnently mounted over the stined tissue to enble fiber clssifiction. Fibers were clssified on the bsis of stin rections: β-red fibers stined drk brown, α-red fibers were cler in the middle nd surrounded by blue ring, nd α-white fibers were cler. Fiber numbers were clculted by exmining minimum of 500 muscle fibers from muscle bundles contining t lest 50 fibers per bundle. Muscle fiber percentge ws clculted by counting the totl number of ech fiber type, dividing by the totl number of fibers counted, nd multiplying the quotient by 100: Fiber Number (%) = Fiber Number (β-red, α-red, or α-white) / Totl Fiber Number * 100. Muscles were clssified s red, intermedite, or white on the bsis of the verge muscle fiber number (%). Muscles were clssified s red if they (Continued on next pge) Pge Nebrsk Beef Report

104 Tble 1. Muscle fiber type chrcteristics of red muscles. β-red α-red α-white MUSCLE Trit Men (S.E. b ) Men (S.E. b ) Men (S.E. b ) Trpezius Number (%) (3.72) (3.08) (2.97) Dimeter (µm) (0.77) (0.91) (0.89) Are (µm 2 ) (42.70) (62.87) (65.06) Percent Are (1.26) (1.36) (1.47) Brchilis Number (%) (2.14) (1.98) 9.10 (1.45) Dimeter (µm) (0.80) (0.95) (0.79) Are (µm 2 ) (44.52) (57.93) (61.16) Percent Are (0.89) (1.06) (1.38) Multifidous & Number (%) (1.90) (2.94) (1.69) spinlus dorsi Dimeter (µm) (0.65) (0.91) (0.89) Are (µm 2 ) (31.51) (54.92) (67.84) Percent Are (0.91) (1.15) (1.34) Biceps brchii Number (%) (1.98) (1.06) (3.02) Dimeter (µm) (0.78) (0.78) (0.77) Are (µm 2 ) (45.61) (48.21) (60.08) Percent Are (0.95) (1.17) (1.29) Intertrnsversles Number (%) (5.84) (3.44) (4.61) Dimeter (µm) (0.88) (0.80) (0.81) Are (µm 2 ) (48.73) (54.59) (57.12) Percent Are (1.03) (1.26) (1.29) Complexus Number (%) (5.95) (1.34) (5.18) Dimeter (µm) (0.69) (1.02) (0.91) Are (µm 2 ) (34.31) (68.80) (68.68) Percent Are (1.02) (1.01) (1.26) Levtores costrum Number (%) (2.65) (4.21) (1.94) Dimeter (µm) (0.92) (1.11) (1.10) Are (µm 2 ) (56.51) (97.39) (98.61) Percent Are (0.85) (1.06) (1.25) Infrspintus Number (%) (3.04) (2.72) (3.55) Dimeter (µm) (0.84) (0.91) (0.98) Are (µm 2 ) (51.67) (67.05) (86.77) Percent Are (0.64) (1.05) (1.24) Brchiocephlicus Number (%) (1.24) (1.01) (1.21) omotrnversrius Dimeter (µm) (0.76) (0.95) (0.87) Are (µm 2 ) (42.04) (67.56) (76.67) Percent Are (0.77) (1.18) (1.24) Longissimus cpitus Number (%) (4.20) (1.30) (4.16) et Atlntis Dimeter (µm) (0.78) (0.92) (0.95) Are (µm 2 ) (43.40) (61.23) (74.79) Percent Are (0.92) (1.16) (1.18) Muscles contining greter thn 40% β - Red fiber numbers were clssified s red. b Stndrd error of the fiber type trits by muscle. hd more thn 40% β-red fibers. White muscles hd more thn 40% α-white fibers, nd ll other muscles were clssified s intermedite muscles. Fiber dimeters were found by cpturing photomicrogrphs with blck nd white, monochrome cmer mounted on light microscope. A minimum of 50 dimeters of ech fiber type (β-red, α-red, nd α-white) were mesured with the help of computer softwre. Muscle fiber re ws clculted from the fiber dimeters: A = π (dimeter/2) 2. Percent re ws clculted for ech fiber type by first multiplying the verge fiber type number by the verge of the fiber re for specific muscle, next, dividing by the totl re, nd finlly, multiplying the quotient by 100: %A = (Averge Fiber Are * Averge Fiber Number (%) / Totl Are ) *100. The nlysis of vrince included muscle nd crcss weight group s min effects. Significnt (P<.05) interctions were seprted using contrsts to test for linerity. Results Tests of the interction of crcss weight group nd muscle nd tests of the effect of crcss weight group on muscle fiber type chrcteristics were not significnt for ny of the chrcteristics studied (P>.05). The effect of muscle on fiber type chrcteristics ws lwys significnt (P<.002). Dt were pooled by muscle, nd mens were clculted for fiber number (%), dimeter, re nd percentge re. Mens re presented by muscle clssifiction in Tbles 1, 2, nd 3. Bsed on the literture, we nticipted fiber-type chrcteristics would be significntly influenced by crcss weight, lthough this is indirectly ssocited with n niml s ultimte size nd ge t slughter. Becuse nimls used 2001 Nebrsk Beef Report Pge 104

105 Tble 2. Muscle fiber type chrcteristics of intermedite muscles. β-red α-red α-white MUSCLE Trit Men (S.E. b ) Men (S.E. b ) Men (S.E. b ) Vstus lterlis Number (%) (4.53) (7.99) (5.02) Dimeter (µm) (0.94) (1.03) (1.11) Are (µm 2 ) (55.51) (78.74) (98.97) Percent Are (0.95) (1.19) (1.16) Subscpulris Number (%) (3.30) (3.70) (1.16) Dimeter (µm) (0.75) (0.84) (0.97) Are (µm 2 ) (40.29) (53.29) (83.46) Percent Are (1.09) (1.17) (1.16) Triceps brchii Number (%) (1.48) (2.10) (2.09) Dimeter (µm) (0.85) (0.93) (1.20) Are (µm 2 ) (45.85) (63.53) (99.82) Percent Are (0.50) (0.99) (1.15) Superficil pectorl Number (%) (4.28) (3.83) (2.24) Dimeter (µm) (0.97) (1.31) (1.06) Are (µm 2 ) (58.51) (115.13) (109.33) Percent Are (1.06) (1.04) (1.15) Teres mjor Number (%) (2.13) (2.15) (3.65) Dimeter (µm) (0.72) (0.73) (0.94) Are (µm 2 ) (33.65) (39.37) (69.70) Percent Are (0.78) (0.86) (1.15) Suprspintus Number (%) (3.09) (4.39) (7.31) Dimeter (µm) (0.89) (1.18) (1.16) Are (µm 2 ) (51.53) (102.24) (106.41) Percent Are (0.98) (1.11) (1.15) Serrtus ventrlis Number (%) (4.96) (2.58) (7.50) Dimeter (µm) (0.92) (1.08) (0.99) Are (µm 2 ) (49.65) (81.88) (79.76) Percent Are (1.05) (1.06) (1.15) Vstus medilis Number (%) (7.66) (2.82) (8.84) Dimeter (µm) (0.71) (1.06) (1.12) Are (µm 2 ) (41.48) (88.76) (110.90) Percent Are (0.56) (1.05) (1.14) Longissimus costrum Number (%) (4.24) (2.74) (3.62) Dimeter (µm) (0.67) (0.94) (0.67) Are (µm 2 ) (31.33) (60.91) (45.06) Percent Are (0.92) (1.02) (1.14) Srtorius Number (%) (2.46) (2.40) (1.79) Dimeter (µm) (0.69) (0.75) (0.73) Are (µm 2 ) (31.40) (42.51) (51.21) Percent Are (0.61) (1.05) (1.12) Deep pectorl Number (%) (2.41) (4.32) (6.11) Dimeter (µm) (0.61) (0.70) (0.68) Are (µm 2 ) (27.01) (38.59) (47.84) Percent Are (0.80) (0.76) (1.12) Splenius Number (%) (0.37) (1.21) (0.98) Dimeter (µm) (0.84) (1.35) (0.94) Are (µm 2 ) (43.42) (93.59) (64.92) Percent Are (0.91) (0.80) (1.12) Muscles not clssified s red or white were clssified s intermedite. b Stndrd error of the fiber type trits by muscle. in this experiment were ll tken from nimls of the sme crcss mturity, it ws thought tht the ultimte size of the nimls from the two different crcss weight groups would significntly influence the muscle fiber type profile. No significnt differences were noted for the weight of the crcss; this likely cn be ttributed to smll smple numbers per weight group (n=2). There were nine of 12 muscles from the round tht were clssified white. The three muscles from the round tht were not clssified s white (Vstus medilis, Vstus lterlis, nd Srtorious) were ll clssified s intermedite. In contrst, muscles of the chuck were evenly dispersed between red (10 of 26), intermedite (9 of 26), nd white (7 of 26). An even distribution of muscle fiber type profiles found in muscles from the chuck would suggest lrge vribility in processing chrcteristics of muscles of the beef chuck. Conversely, muscles of the beef round my be considered similr, nd my not contin s wide vribility in processing chrcteristics s muscles from the beef chuck. 1 Kevin Kirchofer, grdute student. Chris Clkins, Professor, Animl Science, Lincoln. This project ws funded by beef producers through their $1/hed checkoff nd produced for the Cttlemen s Beef Bord nd Stte Beef Councils. (Continued on next pge) Pge Nebrsk Beef Report

106 Tble 3. Muscle fiber type chrcteristics of white muscles. β-red α-red α-white MUSCLE Trit Men (S.E. b ) Men (S.E. b ) Men (S.E. b ) Vstus intermedius Number (%) (5.69) 9.42 (0.85) (5.27) Dimeter (µm) (0.80) (1.02) (1.46) Are (µm 2 ) (48.69) (82.65) (146.93) Percent Are (1.27) 8.16 (1.01) (1.12) Gluteus medius Number (%) (0.80) (2.00) (2.57) Dimeter (µm) (0.85) (1.05) (1.11) Are (µm 2 ) (49.60) (72.70) (88.01) Percent Are (0.99) (1.00) (1.09) Tensor fsci ntibrchii Number (%) (0.68) (3.01) (2.82) Dimeter (µm) (0.82) (0.67) (0.89) Are (µm 2 ) (42.32) (39.61) (72.50) Percent Are (0.69) (0.92) (1.06) Semitendinosus Number (%) (1.97) (1.59) (3.27) Dimeter (µm) (0.87) (0.88) (1.22) Are (µm 2 ) (52.20) (67.92) (121.95) Percent Are (1.06) Biceps femoris Number (%) (1.90) (2.31) (4.02) Dimeter (µm) (0.78) (0.94) (1.12) Are (µm 2 ) (42.76) (69.96) (106.18) Percent Are (1.04) (0.96) (1.05) Deltoideus Number (%) (3.11) (2.24) (3.93) Dimeter (µm) (0.81) (0.85) (1.09) Are (µm 2 ) (40.26) (55.16) (96.26) Percent Are (0.68) (0.80) (1.05) Sclenius dorslis Number (%) (4.00) (1.74) (4.79) Dimeter (µm) (0.57) (0.65) (0.77) Are (µm 2 ) (21.84) (34.74) (51.82) Percent Are (0.89) (0.83) (1.04) Rectus femoris Number (%) (1.43) (3.46) (3.85) Dimeter (µm) (0.74) (0.79) (0.89) Are (µm 2 ) (39.74) (52.99) (68.55) Percent Are (0.70) (1.05) (1.01) Semimembrnosus Number (%) (1.18) (2.02) (2.39) Dimeter (µm) (0.88) (0.97) (1.03) Are (µm 2 ) (54.43) (66.73) (76.95) Percent Are (0.57) (0.83) (1.00) Pectineus Number (%) (5.88) (3.88) (4.79) Dimeter (µm) (0.74) (0.92) (1.08) Are (µm 2 ) (41.73) (60.74) (92.99) Percent Are (0.89) (0.83) (0.98) Rhomboidus Number (%) (2.67) (2.10) (4.16) Dimeter (µm) (0.90) (1.19) (0.91) Are (µm 2 ) (46.91) (80.39) (69.34) Percent Are (0.64) (0.80) (0.98) Ltissmus dorsi Number (%) (3.44) (1.32) (4.46) Dimeter (µm) (0.77) (1.00) (0.94) Are (µm 2 ) (38.95) (62.43) (70.99) Percent Are (0.72) (0.40) (0.97) Dorslis oblique Number (%) (3.10) (2.90) (3.85) Dimeter (µm) (0.64) (0.67) (0.82) Are (µm 2 ) (27.22) (37.54) (59.02) Percent Are (1.29) (1.11) (0.93) Longissimus dorsi Number (%) (1.43) (3.37) (4.41) Dimeter (µm) (0.91) (1.13) (1.26) Are (µm 2 ) (60.92) (98.11) (125.64) Percent Are (1.35) (1.03) (0.90) Adductor Number (%) (2.99) (3.86) (1.87) Dimeter (µm) (0.85) (0.90) (1.01) Are (µm 2 ) (46.79) (58.64) (77.41) Percent Are (1.18) (0.86) (0.84) Grcilis Number (%) (4.12) (4.60) (3.06) Dimeter (µm) (0.63) (0.76) (0.76) Are (µm 2 ) (32.68) (44.25) (51.28) Percent Are (1.37) (1.30) (0.61) Muscles contining greter thn 40% α-white fiber numbers were clssified s white. b Stndrd error of the fiber type trits by muscle Nebrsk Beef Report Pge 106

107 The Effects of Post-Hrvest Time nd Temperture on Glycolytic Potentil of Beef Muscle Dn J. Hnson Chris Clkins 1 Post mortem temperture hs little effect on the extent of glycolysis in beef muscle. The time of post mortem smpling cn impct glycolytic potentil vlues in beef longissimus muscle. Summry The objectives of this study were to determine if post mortem temperture ffects extent of glycogen metbolism nd if smpling time influences glycolytic potentil vlues in muscle. Beef longissimus muscles entered rigor mortis t two different tempertures nd were smpled t 45 minutes post mortem, rigor mortis nd 24 hours post mortem to determine the glycolytic potentil of the muscle. Post mortem temperture hd little effect on the glycolytic potentil of beef muscle. Glycolytic potentil vlues from smples removed erly post mortem were underestimted when compred to smples tken t 24 hours post mortem. Introduction Glycolytic potentil is procedure tht is commonly used to estimte the bility of muscle to generte lctic cid. Ante-mortem muscle glycogen levels cn lso be estimted. Knowledge of muscle s glycolytic potentil cn help studies on drk cutting beef nd other qulity defects. It often is ssumed tht smpling time is not n importnt considertion, becuse the glycolytic potentil procedure mesures glycogen nd some of its degrdtion products; glucose-6-phosphte nd lctic cid. There re number of intermedite products of glycolysis tht re not quntified; their omission might influence the glycolytic potentil vlue. Temperture lso my hve n impct on the extent of glycogen brekdown, post mortem. This my ffect the overll quntities of lctic cid nd residul glycogen in muscle used to determine glycolytic potentil. The objective of this study ws to determine if temperture nd time of muscle smpling ffects glycolytic potentil vlues of beef longissimus muscle. Procedure The right nd left sides from 10 steers were rndomly ssigned to wrm (86 o F) or cold (32 o F) temperture tretments. For the wrm temperture tretment, full, bone-in strip loins were removed immeditely fter slughter nd held t 86 o F until rigor (c. 6 h); then these smples were moved to 32 o F. Cold-temperture loins remined within the crcsses, which were stored t 32 F. Longissimus muscle ph ws mesured every hour to determine rigor (defined s two consecutive ph redings within 0.1 unit). Smples for lctic cid, glycogen nd glycolytic potentil (mmol/kg) were removed 45 minutes post mortem, t rigor, nd 24 hours post mortem. Glycolytic potentil is procedure tht mesures the potentil for lctic cid production by the muscle. Knowledge of glycogen, glucose-6-phosphte, nd lctic cid concentrtions (determined enzymticlly) llows glycogen levels to be clculted becuse ech molecule of glycogen genertes two molecules of lctic cid. These smple were frozen in liquid nitrogen nd stored t -112 o F until further nlysis. Three, 1-inch thick steks were cut from ech loin section to be used for Wrner-Brtzler sher determintion fter one, seven nd 14 dys of ging. Steks were cooked on tble-top broilers to 158 o F prior to cooling for removl of 1/2-inch cores. Results Longissimus muscle ph did not differ between hot- nd cold-treted muscle t 24 hours (P<.05). The rte of ph decline ws different mong the temperture tretments, but this hd no effect on the finl vlues. These ph dt re summrized in Tble 1. With the exception of lctic cid levels (P<.05) t 24 h, temperture t storge (wrm vs cold) hd no significnt effects on lctic cid, glycogen nd glycolytic potentil t 45 minutes post-mortem (Tble 2), t the point of rigor development (Tble 3), or 24 hours post mortem (Tble 4). Clerly storge (Continued on next pge) Pge Nebrsk Beef Report

108 Tble 1. Men ph vlues t three different times post mortem for beef longissimus muscle held t two different tempertures post mortem. Smpling Time Wrm Cold b P vlue 45 min post mortem Estimted rigor c < h post mortem Wrm = 86 o F. b Cold = 32 o F. c Estimted rigor = the time when consecutive, hourly ph redings were within 0.1 unit. Tble 2. Pre-rigor glycogen, lctte, nd glycolytic potentil vlues for beef longissimus muscle held t two different tempertures post mortem. Smpling Time Wrm Cold b P vlue Glycogen c, mmol/kg Lctte, mmol/kg Glycolytic potentil d Wrm = 86 o F. b Cold = 32 o F. c Glycogen = ([glycogen] + [glucose] + [glucose-6-phosphte]). d Glycolytic Potentil (mmol of lctte equivlents / kg of wet tissue). This is determined s (2 x glycogen) + lctte concentrtions. Tble 3. Glycogen, lctte, nd glycolytic potentil vlues t rigor onset for beef longissimus muscle held t two different tempertures post mortem. Smpling Time Wrm Cold b P vlue Glycogen c, mmol/kg Lctte, mmol/kg Glycolytic potentil d Wrm = 86 o F. b Cold = 32 o F. c Glycogen = ([glycogen] + [glucose] + [glucose-6-phosphte]). d Glycolytic Potentil (mmol of lctte equivlents / kg of wet tissue). This is determined s (2 x glycogen) + lctte concentrtions. Tble 4. Post mortem (24 h) glycogen, lctte, nd glycolytic potentil vlues for beef longissimus muscle held t two different tempertures post mortem. Smpling Time Wrm Cold b P vlue Glycogen c, mmol/kg Lctte, mmol/kg Glycolytic potentil d Wrm = 86 o F. b Cold = 32 o F. c Glycogen = ([glycogen] + [glucose] + [glucose-6-phosphte]). d Glycolytic Potentil (mmol of lctte equivlents / kg of wet tissue). This is determined s (2 x glycogen) + lctte concentrtions. Tble 5. Wrner-Brtzler sher (lb) vlues t three different ging times for beef longissimus muscle held t two different tempertures post mortem. Smpling Time Wrm Cold b P vlue 1 dy of ging dys of ging < dys of ging <.01 Wrm = 86 o F. b Cold = 32 o F. temperture (or temperture t rigor) hs little influence on the extent of post mortem glycolysis. Time of storge ltered the clculted glycolytic potentil in this study. These vlues incresed from to mmol/kg over 24-hour period (P<.05) in wrm-treted muscle nd from to in cold-treted muscle. Vlues t 24 hours for wrm versus cold muscle were not different (P =.86). These dt suggest tht glycolytic potentil will be underestimted if muscle smples re tken t 45 minutes post mortem. It is likely tht substrte (glycogen) is cught in the vrious stges of glycolysis. These intermedite products of glycolysis re not mesured by the glycolytic potentil ssy. It ppers tht pre-rigor muscle smples intended for determintion of glycolytic potentil should be llowed to fully metbolize prior to mesurement. In this study, wrm tretment ws ssocited with elevted (P<.05) sher force vlues t one, seven nd 14 dys of ging compred to cold-treted muscle. Perhps the more rpid rte of ph decline in wrm-treted muscle did not llow sufficient time for proteolytic enzymes to brek down the muscle ultr structure before the ultimte ph ws chieved. The men ph vlues fter six hours post mortem for cold-treted muscle were higher (P<.01) thn the wrm treted-muscle, 5.54 vs 5.33, respectively. The proteolytic enzymes my hve been irreversibly dentured by the low ph, high temperture condition, which would explin the lck of tenderness improvement on dys 7 nd 14 for the wrm-treted muscle. It cn be concluded tht temperture hs little effect on the extent of post mortem glycolysis in muscle. Mesuring glycolytic potentil prior to rigor mortis underestimtes glycogen by 10-15%. This my be due to the concentrtion of intermedite products of glycolysis. Muscle smples for determintion of glycolytic potentil should be tken fter rigor to void underestimtion of glycogen in beef longissimus muscle. 1 Dn J. Hnson, grdute student; Chris Clkins, professor, Animl Science, Lincoln Nebrsk Beef Report Pge 108

109 The Role of Muscle Glycogen in Drk Cutting Beef Dn J. Hnson Chris Clkins Kevin Kirchofer 1 Pre- slughter glycogen levels need to be greter thn 80 mmol/kg to prevent the drk cutting beef condition. Summry Drk cutting beef occurs when muscle glycogen levels re depleted prior to slughter. Without glycogen, lctic cid is not produced in postmortem muscle, cusing higher thn norml muscle ph. This reserch ws conducted to identify the threshold level of glycogen where the drk cutting condition is likely to occur. These dt from muscles vrying widely in ph suggest tht muscle glycogen levels need to be t or bove 80 mmol/kg to prevent the drk cutting beef condition. Introduction Crbohydrtes re stored s glycogen in muscle. Glycogen provides energy for the muscle cell to function. This crbohydrte, through conversion to lctic cid, fcilittes the norml ph drop tht occurs when muscle is converted to met fter slughter. Glycogen tht hs been stored in the muscle continues to be metbolized post mortem. This degrdtion of glycogen produces lctic cid nd cuses the ph of the muscle to drop. Normlly, muscle glycogen concentrtions re sufficient to drive the ph of the muscle to pproximtely 5.6. If the niml hs been exposed to lrge mount of stress (hrsh wether, excessive exercise, lck of wter or feed, mixing with unfmilir nimls, or estrus) prior to slughter, the mount of glycogen in the muscle cn be severely reduced. In this cse, drk cutting beef cn occur. This is due to the lck of glycogen needed to fcilitte drop in muscle ph fter deth. Drk cutting beef hs ph greter thn 5.8 nd cn be s high s 6.9. This muscle is drk in color, undesirble in flvor, nd more susceptible to microbil spoilge. As result, prices pid to producers re severely reduced when this condition occurs. There re limited dt regrding muscle glycogen concentrtions needed to prevent the drk cutting beef condition. The objective of this study ws to determine the level of pre-slughter glycogen tht is required to prevent drk cutting beef. This informtion my be helpful in designing strtegies to reduce the occurrence of this condition. Procedure Drk cutting nd norml colored muscle smples (n=180) were collected from two mjor pckers in the stte of Nebrsk. These smple were obtined by removing pproximtely 100 g from the 12th rib region of beef crcsses 2-4 dys post mortem. Color scores (L*, mesures the reltive lightness nd drkness of color; *, mesures the reltive greenness to redness color of smple; b*, mesures the reltive yellowness to blueness of color) were lso tken just prior to removl of the smple. Smples with high ft content (> 6.0 %) were removed from the originl dt set. It ws concluded tht high ft smples cuse n overestimtion of L* vlue due to the mount of white color provided by the ft in the smple. A visul color scle ws used to clssify smples (n=121) bsed on the drk to norml color rnge of the muscle. A score of 1 represented normlppering muscle nd 5 represented extremely drk muscle. Smples were frozen on dry ice nd stored t - 22 F before nlysis for glycolytic potentil (glycogen content) nd ph. Glycolytic potentil is procedure tht mesures the totl mount of lctic cid produced by the muscle s well s the glycogen remining in the system. The lctic cid vlues cn be converted to glycogen becuse ech molecule of glycogen genertes two molecules of lctic cid. These dt essentilly indicte the mount of glycogen tht ws present in the muscle system before deth. Regression nlysis ws used to determine the reltionship between glycogen concentrtion nd ph. The chrcteristics for ech color score were evluted by nlysis of vrince. Mens were then seprted using t-tests. Results The dt collected reveled significnt qudrtic reltionship (Figure 1) between pre-slughter glycogen levels nd ph (R 2 =.83, root men squre error = 8.6.), where ultimte ph decresed with incresing glycogen level. Figure 1 lso shows the reltionship of residul glycogen to ph (R 2 =.63, root men squre error = 7.7). A very strong liner reltionship exists between muscle glycogen concentrtion nd ph for ph vlues bove 5.6. In this ph rnge, residul glycogen levels pper to consistently rech bout 12 mmol/kg. For this prt of the curve, post-mortem conversion of muscle glycogen to lctic cid seems to continue until this bseline level of glycogen remins. The result is stedy decline in ph with incresing levels of muscle glycogen t slughter. Below ph 5.6, however, the reltionship of nte-mortem muscle glycogen to ph is drmticlly different. In this (Continued on next pge) Pge Nebrsk Beef Report

110 Residul Glycogen Ante-mortem Glycogen Glycogen concentrtion mmol/kg R 2 =.82, RMSE = 8.6 R 2 =.63, RMSE = ph Figure 1. Comprison of estimted nd residul glycogen in popultion of norml nd drk cutting beef. Tble 1. Men vlues for ph, L*, *, b*, residul glycogen, nd nte-mortem glycogen seprted by visul color score. Visul Color Score n Ultimte muscle ph b 6.05 c 6.31 d 6.72 e L* b b c * c b b b b b* d b b bc c Residul glycogen, b c c c mmol/kg Ante-mortem glycogen, b c d d mmol/kg bcd Mens within row with unlike superscripts differ (P<.05). Color score, 1 = norml muscle color ; 5 = extreme drk cutting beef color. b Lightness: 0 = blck, 100 = white. c Red to green: - 60 = green, + 60 = red. d Blue to yellow: - 60 = blue, + 60 = yellow. sitution, glycogen levels bove 80 mmol/kg do not result in consistently lower ph vlues. In fct, residul glycogen levels in post mortem muscle increse. These vlues re not lowered to the 12 mmol/kg level noted t ph vlues bove 5.6. The pprent reson is tht ph vlues below 5.6 seem to inctivte the enzymes responsible for glycogen degrdtion. Thus, muscle glycogen levels t deth of 80 mmol/kg or more re sufficient to reduce ultimte ph levels in post-mortem muscle nd void the drk cutting condition. Muscle L*, * nd b* vlues hd significnt curviliner reltionships (dt not shown) to ph (R 2 =.34,.64 nd.60, respectively). These reltionships were lower thn expected. The L*, * nd b* redings represent point in three-dimensionl color system. For exmple, two smples my hve identicl L* nd * redings yet one smple my pper to hve n ornge hue while the other ppers purple. Ech color occupies certin point within the 3-D color spce. Drwing conclusions from single prmeter (L*, *, b*) should be mde with cution. Visul color scores in this study proved to be more effective mens in which to segregte crcsses bsed on their overll color. Mens from the visul color scle re presented in Tble 1. The visul color scle ws used to clssify beef crcsses bsed on the perceived severity of drk cutting. Significnt differences (P<.05) mong visul ctegories were noted for ph. All glycogen levels were significntly different from ech other (P<.05), except those for scores 4 nd 5 (P =.08). These dt suggest tht visul ssessment of color cn be effective in clssifying drk cutting beef. Currently, the USDA grding system uses this type of subjective mesure of color to clssify drk cutters. These dt suggest tht this pproch is vible. Results from this study indicte tht the drk cutting condition is more likely to occur when muscle glycogen levels re below 80 mmol/kg. With this informtion, mngement strtegies prior to slughter could be developed to reduce the incidence of drk cutting beef. 1 Dn J. Hnson nd Kevin Kirchofer, grdute students; Chris Clkins, professor, Animl Science, Lincoln. This project ws funded by beef producers through their $1/hed checkoff nd produced for the Cttlemen s Beef Bord nd Stte Beef Councils Nebrsk Beef Report Pge 110

111 Dietry Conjugted Linoleic Acids (CLA) nd Body Ft Chnges Jess Miner Chris Cederberg Merlyn Nielsen Xioli Chen Clifton Bile 1 Conjugted linoleic cid consumption by mice reduced body ft. A prllel effect is implied for humns tht consume beef. Summry A mixture of CLA isomers ws fed to mice t 0, 1, nd 2% of the diet for 5, 12, or 14 dys. Dietry CLA cused reduction of body ft pproching 50% but did not cuse loss of totl body weight. Mice fed CLA lso experienced progrmmed cell deth (poptosis) of ft cells. Certin (not ll) CLA isomers re nturl components of beef nd diry products but not other foods. Therefore, these observtions prompt specultion of n dditionl helth benefit, reduced diposity to humns tht et ruminnt-derived foods. Introduction Conjugted linoleic cids (CLA) re produced by nerobic ruminl metbolism nd subsequent niml metbolism. Consequently, ruminnt niml fts contin substntil CLA (~.5%) nd re by fr the predominnt source of CLA in the humn diet. Initil investigtions reveled cncer-preventing effects of CLA. Others hve reported tht feeding CLA to mice for 6 weeks cn increse energy expenditure nd reduce body ft. The mechnism by which CLA medite these effects is uncertin, but there is evidence tht CLA influence expression of ft metbolizing genes. The objective of our reserch ws to determine effects of feeding CLA to mice on energy expenditure, feed intke, body ft nd poptosis in white dipocytes. The rtionle is tht the response of mice to dietry CLA my predict the response of humns to dietry beef or diry fts. Diets Procedure Conjugted linoleic cid ws mixed into purified bse diet. Soy oil ws replced (1:1) with CLA to crete diets of 0, 1 nd 2% CLA. This CLA is mixture of isomers with pproximtely 44% being the type (c9/t11) tht predomintes in ruminnt fts, nd 41% is t10/c12. Experiment 1 Ninety 10- to 12-wk-old mle mice were housed individully t 22 o C nd rndomly ssigned to one of the three experimentl diets. Feed intke nd body weight were mesured dily. Direct clorimetry ws used to mesure het loss during four-hour period beginning t 1700 on dy 9 for ech replicte. On the dy of clorimetry, feed ws unvilble from 1200 until Thus, het loss ws determined in the fsted nd in the refed stte for ech niml. Het loss ws determined t one-minute intervls nd collected every 30 minutes for two hours in ech stte. Wter ws not vilble in the clorimeter chmbers. Three dys fter clorimetry, between 0800 nd 1000, mice were scrificed by CO 2 sphyxi. Brown, epididyml nd retroperitonel ft pds nd livers were removed nd weighed. Twenty-one retroperitonel ft pds were nlyzed for poptosis (progrmmed cell deth) by DNA lddering ssy. Experiment 2 Twenty obese M16 strin retired mle breeders were rndomly ssigned to one of three CLA diets: 1) 0% for 12 dys; 2) 2% for 14 dys; nd 3) 0% for 9 dys followed by 2% for 5 dys. Body ft, body weight, nd poptosis were ssyed s in experiment 1. Experiment 1 Results Feed intke (g/dy) by mice fed 0, 1, nd 2% CLA for 12 dys ws 5.0, 4.7, nd 4.4 (SE =.11; P <.05) respectively. Despite consuming less feed, the mice fed 1 nd 2% CLA expended s much energy s the controls. After consuming CLA for 12 dys, mice hd considerbly less body ft thn contemporries which were not fed CLA (Figure 1). The ft cells from mice fed 2% CLA presented more poptosis thn cells from control mice (P <.10). Experiment 2 Consumption of 2% CLA diet for either five or 12 dys cused significnt loss of body ft in ll of the depots mesured (Figure 2). In spite of this (Continued on next pge) Pge Nebrsk Beef Report

112 grms Figure 1 grms % CLA BAT EPI RP Liver/10 Experiment 1 Weight of Brown (BAT), Epididyml (EPI), nd Retroperitonel (RP) Ft Pds, nd of Liver (scled to 10% of ctul weight). ** CLA effect (P<.01). * CLA effect (P<.10). Error brs represent SEM Dys of CLA loss of body ft, totl body weight incresed in nimls fed CLA versus control (P <.05). Consistent with the results of experiment 1, nlysis of retroperitonel ft pds indicted tht dietry CLA cused progrmmed cell deth in ft cells (P <.03). In conclusion, feeding mixed isomers of conjugted linoleic cid to mice cuses rpid (within 5 d) loss of body ft, no loss of totl body weight, nd ppers to cuse poptosis of ft cells. Perhps this poptosis medites the specific loss of body ft cused by CLA consumption. It is inviting to hypothesize tht ruminnt niml-derived humn foods cn provide n nti-obesity benefit. This conclusion cnnot be drwn with much certinty t the moment. Although ruminnt fts re the only significnt source of CLA in the humn diet, most of the CLA in ruminnt ft is c9/t11. Our experimentl CLA mixture contined nerly s much t10/c12 s it did c9/t11. Therefore, the effect we observed in mice could be due to n isomer of CLA which is not predominnt in ny food. Furthermore, there is question bout whether the mount of CLA necessry to cuse benefit could be supplied by reltively norml diet. Certinly, the mount of CLA which we fed mice (1% nd 2%) couldn t be obtined nturlly given tht beef nd milkft re.5% CLA. However, some reserch conducted t the University of Georgi indictes tht.25% CLA cuses loss of body ft in rts. We hve not tested such low concentrtions. 0 SC EPI RP BAT Figure 2. Experiment 2 Weight of Subcutneous (SC), Epididyml (EPI), Retroperitonel (RP), nd Brown (BAT), Ft Pds. ** CLA effect (P<.01). Error brs represent SEM. 1 Jess Miner nd Merlyn Nielsen, Animl Science, Lincoln; Chris Cederberg, undergrdute honors student; Xioli Chen, grdute student, Clifton Bile, Animl Science, University of Georgi Nebrsk Beef Report Pge 112

113 Chnges to the Purine Assy Improve Purine Recovery nd Assy Precision Ryn Mss Kelly Creighton Terry Klopfenstein 1 Modifictions of the purine ssy improved recovery of purines, incresed ssy precision, nd ccounted for prticle-ttched bcteri. Summry Three experiments tested modifictions of the purine ssy designed to improve estimtion of microbil crude protein supply. In Experiment 1, chnging hydrolysis conditions from 12 norml perchloric cid to 2 norml incresed purine recovery nd lowered the coefficient of vrition. In Experiment 2, phosphte buffer yielded greter recovery of purines thn cette buffer nd using the extrction solution s wsh ws less vrible thn silver nitrte in.005 molr hydrochloric cid. In Experiment 3, purine nitrogen:totl microbil nitrogen rtios for five forges were determined by incubting NDF in situ nd nlyzing them before nd fter neutrl detergent extrction. Introduction The originl purine ssy hs two problems. First, the current method of isolting rumen microbes, known s differentil centrifugtion, my not yield representtive proportion of prticle-ttched microorgnisms. Therefore, the mesured purine nitrogen:totl microbil nitrogen rtio of those microbes my not be ccurte. Second, purine recovery nd the precision ssocited with tht recovery re poor. Two lbortories (in Germny nd t Ohio Stte University) hve proposed seprte modifictions to the ssy tht improve recovery of purines. The objectives of this reserch were to develop method of estimting the purine nitrogen:totl microbil nitrogen rtio of prticle-ttched microorgnisms nd to investigte the effect combintions of these modifictions hve on purine recovery nd precision. Procedure Three experiments were conducted. Smples for Experiments 1 nd 2 were collected from five ruminlly nd duodenlly fistulted steers (ve wt. = 800 lb) tht were fed lflf hy nd smooth bromegrss hy for seven dys ech. Cttle were fed hy d libitum for six dys nd omsl, duodenl nd fecl smples were collected on the seventh dy. All smples were lyophilized nd ground by Wiley mill to pss through.008" screen. Experiment 3 ws n in situ experiment tht used both the lflf nd smooth bromegrss hys from the previous experiments s well three other hys: switchgrss hy, high-qulity medow hy nd lowqulity medow hy. The qulity of these forges is described in Tble 1. In Experiment 1, the 10 omsl smples were used. The objective ws to test the effect of perchloric cid concentrtion on purine recovery within the originl protocol of Zinn nd Owens. Tretments were 12 or 2 norml perchloric cid. In Experiment 2, the effects of buffer type nd wsh solution within the Zinn nd Owens procedure were tested in 2 x 2 fctoril rrngement. Smples tested were the duodenl smples tht correspond to the sme smpling time s the omsl smples in Experiment 1. Buffers tested were.2 molr cetic cid nd.2 molr mmonium phosphte. Wsh solutions tested were.005 molr silver nitrte nd the originl precipittion solution of the procedure. The perchloric cid used in Experiment 2 ws 2 norml. In Experiment 3, the objective ws to estimte the purine nitrogen:totl microbil nitrogen rtio of prticlettched rumen microorgnisms. Neutrl detergent fiber (NDF) ws generted for ech forge nd dried NDF ws incubted in situ for 12 hours. Three bgs ech were incubted in steer fed 2% of body weight of smooth bromegrss (8% CP) nd nother steer fed 2% of body weight of diet contining 70% of the DM s tht smooth bromegrss hy nd 30% of the DM s 50:50 blend of dry-rolled corn nd soyben mel. Nitrogen nd purine concentrtions were mesured on the NDF before ruminl incubtion nd on the in situ residue both before nd fter neutrl detergent extrction. Results Results of Experiment 1 re shown in Tble 2. Use of 2 norml perchloric cid incresed purine recovery over the stndrd 12 norml cid. Estimtes of microbil crude protein concentrtion incresed from 2.23% to 7.43% of the DM. The less concentrted cid lso lowered the coefficient of vrition (CV), n estimtion of the method s error rte, from 14.87% (when 12 norml cid ws used) to 3.14%. These results re in greement with two other reserch publictions. The more concentrted cid genertes chemicls in the smple tht interfere with the detection of purines, thereby reducing purine concentrtions. This effect occurs only when NDF is present in the smple; this (Continued on next pge) Pge Nebrsk Beef Report

114 Tble 1. Qulity of hys used in experiments. Forge CP UIP NDF Alflf Smooth bromegrss Switchgrss High-qulity medow hy Low-qulity medow hy CP, UIP (in situ NDIN procedure), nd NDF on DM bsis. Tble 2. Effect of cid concentrtion on purine recovery (Experiment 1). perchloric cid normlity Item 2 N 12 N SEM P-vlue MCP 7.43 c 2.23 d C.V. b 3.14 c d Microbil crude protein (DM bsis), s estimted by purines (purine nitrogen:totl nitrogen rtio ssumed to be.2). b Coefficient of vrition for MCP estimtes, % of men vlue. c,d Mens within row with different superscripts differ (P-vlue shown). Tble 3. Effects of buffer nd wsh solution type on purine recovery (Experiment 2). cette buffer phosphte buffer Effects AGNO3 b ORIGINAL AGNO3 ORIGINAL buffer wsh buffer *wsh MCP c CV d P-vlues for effects listed. b AGNO3 is silver nitrte wsh solution; originl is the sme wsh solution s is used for the extrction. c Microbil crude protein (DM bsis), s estimted by purines (purine:n rtio ssumed to be.2). d Coefficient of vrition for MCP estimtes, % of men vlue Alflf Brome HQH LQH SWITCH Figure 1. Purine nitrogen:totl microbil nitrogen rtio of prticle-ssocited rumen microorgnisms on NDF of different forges (Experiment 3). HQH, LQH, SWITCH = high nd low-qulity medow hy, nd switchgrss, respectively.,b,c Brs within unlike letters differ (P <.06). is the cse with omsl nd duodenl smples. The reduction of CV when weker cid is used is lso beneficil, s the stndrd purine ssy is known to be vrible. Finlly, use of weker cid lso mkes the ssy sfer becuse smples will be less prone to explode. b In Experiment 2, phosphte buffer incresed purine recovery when compred to cette buffer (Tble 3). The use of the originl precipittion solution s wsh solution lso resulted in significntly greter purine recovery thn did the silver nitrte solution. There ws c no effect of buffer type or wsh solution on the CV of the MCP estimte (Tble 3). Therefore, the combintion of phosphte buffer nd the originl precipittion solution for wshing the smple pellet should be used to chieve the mximum recovery of purines in smple. The purine nitrogen:totl microbil nitrogen rtios mesured in Experiment 3 re shown in Figure 1. There ws no effect of fistulted steer diet on the rtios so the dt were pooled cross diets. Alflf, bromegrss nd high-qulity medow hy were not different in terms of rtio (~.28). Low-qulity medow hy s rtio (.361) ws sttisticlly different thn ll forges, s ws switchgrss (.417). Ech of these estimtes differs from the previous estimte mde t UNL for bromegrss (.137; 1998 Nebrsk Beef Report, pp ) but fll within the rnge of those estimtes mde t Ohio Stte University (rnging from.207 to.587). Becuse this rtio converts purine vlues to MCP vlues, it hs substntil effect on MCP clcultions. Rtio estimtes re typiclly mde by the differentil centrifugtion of rumen contents. This method effectively seprtes free-floting rumen microbes from forge prticles; however, those microbes ttched to forge prticles tend to remin with the forge. This is problemtic becuse mjority of the rumen microbes re ttched to forge prticles when forge diets re fed. If the purine nitrogen:totl microbil nitrogen rtio of prticle-ssocited microbes differs from tht obtined by differentil centrifugtion, estimtes of MCP will be inccurte. Our dt suggest the rtio is vrible nd cn be ffected by forge type. This reserch estblishes modified purine ssy tht ccurtely estimtes the MCP concentrtion of digest smple. The improved method of estimting the purine nitrogen: totl microbil nitrogen rtio tht includes prticle-ssocited microbes, mjor source of microbil protein, cn be used for forge diets. 1 Ryn Mss nd Kelly Creighton, grdute students; Terry Klopfenstein, professor. Animl Science, Lincoln Nebrsk Beef Report Pge 114

115 Urinry Allntoin Excretion s Mrker of Microbil Crude Protein Supply for Cttle Ryn Mss D.J. Jordon Tony Scott Dvid Hrmon Todd Milton Terry Klopfenstein 1 Urinry llntoin excretion cn be used s n estimte of microbil crude protein supply. Summry Two metbolism trils evluted urinry llntoin excretion s noninvsive mrker of microbil crude protein flow from the rumen. In the first tril, both urinry llntoin excretion nd duodenl purine flow incresed s lflf intke incresed. A positive liner reltionship (r 2 =.74) existed between the mrkers. In the second tril, n increse in the metbolizble energy supplied to the niml did not increse urinry llntoin excretion. We concluded tht urinry llntoin excretion ws n effective, noninvsive mrker of microbil crude protein supply. Introduction A urine metbolite, llntoin, hs received recent ttention in diry nd sheep reserch for its potentil to serve s microbil crude protein (MCP) mrker. No vlidtion studies hve been conducted tht compre urinry llntoin excretion (ALLAN) to duodenl flow of MCP for beef cttle diets. Such comprison would provide benchmrk for the use of ALLAN in field trils. It my be inccurte to ssume ALLAN is the sme for ll dietry conditions. The objectives of the reserch reported herein were: 1) to compre ALLAN to the duodenl flow of MCP mesured by purines; 2) to describe the effect of incresing lflf hy intke on the vribles in objective 1); nd 3) to investigte effects of metbolizble energy supply on ALLAN. Procedure Six crossbred yerling steers (men wt = 800 lb.) were fitted with ruminl nd duodenl cnnule ccording to the guidelines of the UNL Institutionl Animl Cre nd Use Committee. The diet fed in two metbolism trils ws single lot of lflf hy (DM bsis): 22.4% CP, 32.8% NDF, nd 26.7% ADF. A pre-tril feeding period determined the mximum level of dry mtter intke tht ll steers would sustin without ny feed refusl ws 19 lb/dy.in Tril 1, frctions of the mximum level were pplied s tretments in concurrent 3 x 3 Ltin squre rrngement: 1) 9.5 lb/dy; 2) 14.3 lb/dy; or 3) 19 lb/dy. Periods were 21 dys. Hy ws fed every 2 hours by utomtic feeders in n ttempt to estblish stedy stte of fermenttion in the rumen. Steers were housed in 10' x 10' box stlls nd were llowed to move freely on dys 1-14 of ech period. On dys 15-21, steers were tethered to fcilitte smple collection. Duodenl smples were collected every 3 hr from 0700 to 1900 on dys nd totl urine collection ws mde on dys by bdominl funnels ttched to vcuum pump. Duodenl smples were freeze-dried nd nlyzed for purines s microbil mrker nd cid-insoluble sh s flow mrker. Aliquots of ech totl urine collection were nlyzed for llntoin. Tril 2 ws conducted s follow-up to Tril 1. The following two tretments were pplied over six-dy periods in crossover design: 1) 14.3 lb/dy of lflf hy DMI plus ruminl infusion of isotonic sline; or 2) 14.3 lb/dy of lflf hy DMI plus ruminl infusion of sodium cette nd propionic cid solution (ph = 6.0) formulted to provide the metbolizble energy equivlent of 4.7 lb of lflf hy DMI. The ruminl infusions were given s pulse doses through the ruminl cnnul four times dily. Cttle were tethered on dys 4-6 nd totl urine collections were mde t tht time. Aliquots of urine were nlyzed for llntoin. Results A direct comprison of the dily supplies of purines nd llntoin (Figure 1) indictes there is liner reltionship between them. The fit of the line (s described by the r 2 vlue) implies the line does n dequte job of describing the vrition between the two methods. An r 2 vlue of.74 cn be interpreted s the line describing 74% of the vrition in the dt. The fct tht the slope of the line (.84) is less thn one indictes tht not ll of the dily purine flow t the duodenum is recovered in the urine s llntoin. Slopes of less thn one for comprisons between post-ruminl purine flow nd ALLAN hve been reported in the scientific literture. The possibility exists for purines to be metbolized to derivtives other thn llntoin nd excreted in the urine. The effect of lflf DMI on the supply of ech MCP mrker is shown in Figure 2. The upwrd slope of the regression lines for both purine nd llntoin indictes n increse in lflf intke cused n increse in MCP mrker supply. This is intuitively correct; n (Continued on next pge) Pge Nebrsk Beef Report

116 Allntoin, mmol/dy y = 0.84x R 2 = Purines, mmol/dy Figure 1. Comprison of duodenl purine flow nd urinry llntoin excretion in beef cttle. The dotted line represents 100% recovery of purines s urinry llntoin. The solid line represents the ctul recovery of purines s llntoin (eqution for solid line shown on grph). Mrker supply, mmol/dy y = R 2 = 0.63 Purine y = 13.09x R 2 = 0.86 Allntoin Alflf DMI, lb Figure 2. Effect of lflf dry mtter intke on microbil crude protein mrker supply. increse in the TDN vilble for rumen fermenttion should increse the mount of microbil cells nd constitutive MCP mrkers. The degree of fit for ech regression eqution is lso shown. The higher r 2 vlue for llntoin (.86) indictes it does better job of describing the increse in MCP supply cused by dditionl lflf DMI thn the does the purine ssy (.63). This my be becuse the compound errors ssocited with the mesurement of purine supply in duodenl smples led to more vrition in those estimtes. Both n MCP mrker (purine) nd duodenl flow mrker (cid-insoluble sh, in this tril) re incorported into duodenl supply estimte, wheres urine excretion estimte is bsed only on one mrker (llntoin). There ws no difference in the urinry excretion of llntoin for the tretments imposed in Tril 2 (dt not shown). The overll men llntoin excretion (mmol/dy) for Tril 2 ws mmol/dy. This vlue is similr to the men llntoin excretion (119.7 mmol/dy) for the cttle fed the sme level of lflf DMI in Tril 1. The experimentl infusion of voltile ftty cids in Tril 2 ws designed to provide the metbolizble energy equivlent of 4.7 lb of lflf DMI without llowing the rumen bcteri ccess to the energy. The hypothesis being tested ws whether or not the dditionl metbolizble energy provided to the niml by the dded lflf incresed the endogenous excretion of llntoin. We conclude metbolizble energy level hs no effect on endogenous llntoin excretion nd ll the increse in llntoin exhibited by incresed lflf DMI in Tril 1 is due to rumen microbes. Allntoin is the product of heptic oxidtion of purines nd is clered by the kidney t rpid rte. Intermedite products of this oxidtion (such s xnthine nd uric cid) do occur in the urine, but they re smll frction of the totl oxidized purines (.k.. purine derivtives), so we did not nlyze for them. Another reson we did not nlyze for the other purine derivtives is tht our ssy is only specific for llntoin. While other ssys exist tht do mesure ll the purine derivtives, they re more complex to perform. We conclude there is strong liner reltionship between duodenl purine flow nd urinry llntoin excretion. This reltionship llows the use of llntoin s noninvsive mrker of MCP supply. Urinry llntoin excretion is simpler method of estimting MCP supply thn the duodenl purine method. Further reserch will focus on describing the reltionship between these MCP mrkers nd the ctul mount of microbil crude protein they represent. 1 Ryn Mss, grdute student; D.J. Jordon nd Tony Scott, technicins; Todd Milton nd Terry Klopfenstein, ssistnt professor nd professor; UNL niml science, Lincoln Dvid Hrmon, professor, University of Kentucky Animl Science, Lexington Nebrsk Beef Report Pge 116