Monensin and Extruded Urea-Grain for Range Beef Cows

Transcription

1 Mnensin and Extruded Urea-Grain fr Range Beef Cws R. P. Lemenager, F. N. Owens, w. E. Sharp, Merwin Cmptn and Rbert Ttusek Stry in Brief Tw trials were cnducted t evaluate the supplemental value f mnensin and extruded urea-grain in cmparisn t natural prtein (30 and 15%) supplements fr beef cws grazing lw quality dry winter range grass. The extruded urea-grain supplement (30% prtein) cntained ne-half f its prtein equivalent frm urea. Cw weight change was nt cnsistently affected by mnensin. Cws wintered n 30% natural prtein supplement lst less weight than cws receiving 15% natural prtein supplement r a supplement cntaining extruded urea-grain. Calculatins indicated the urea in extruded ureagrain was utilized abut 43% as well as natural prtein. Cnditin scre lss f cattle fllwed the same trend as weight lss, with cattle lsing the mst weight als lsing the mst cnditin. Mnensin supplemented cws did nt differ appreciably frm cws receiving cntrl supplements in ruminal ttal nitrgen, ammnia, nnammnia nitrgen r sdium. Hwever, additin f mnensin t supplements decreased ruminal mlar percent f acetate and butyrate, and increased ruminal prpinate and ruminal ptassium. This experiment indicated that (1) urea frm extruded urea-grain is nt utilized as well as natural prtein by cws n dry grass, and (2) mnensin did nt decrease winter weight lss f range cws. The pssibility that mnensin decreases the intake f frage by range cws is nw being researched. Intrductin Altering ruminal fermentatin t favr prpinic acid prductin by the micrrganisms shuld increase feed efficiency. Imprved feed efficiency wuld be expected since previus research has indicated that (1) prpinic acid fermentatin is energetically mre efficient, (2) prpinic acid is utilized by the hst animal mre efficiently, and (3) prpinic acid may have a prtein sparing effect as a precursr f glucse. l\inensin has been shwn t increase the mlar prprtin f rumen 54 Oklahma Agricultural Experiment Statin

2 prpinic acid bth in the labratry and in the rumen f cattle fed a high grain ratin and t increase feed efficiency f cattle fed finishing ratins. Cattle n pasture have shwn increased mlar prprtins f rumen prpinate and imprved average daily gains when fed mnensin. Labratry experiments indicated that mg/head/day is ptimal fr cattle fed high rughage diets. The purpse f this study was (1) t evaluate the additin f mnensin t supplements fr pregnant and lactating cws, and (2) t determine the utilizatin f extruded urea-grain in a supplement cntaining alfalfa fr cws. All cws grazed dry winter range grass during the experiments. Prcedure Tw winter trials were cnducted in Central Oklahma n native tall-grass range with climax vegetatin f little bluestem, big bluest em, Indian grass and switch grass. Ingredient makeup f experimental supplements is shwn in Table 1. The nitrgen:sulfur rati fr all supplements was apprximately 12: 1. Initial and final weights, and visually appraised cnditin scres were btained after a l2-hur shrink. A cnditin scre f 1 t 9 was placed n each individual cw with 1 being the thinnest and 9 the fattest rating. Trial 1. Seventy-eight mature Angus and Herefrd cws were randmly alltted, after blcking by breed and breeding date, t six treatments fr a 107-day wintering trial. The six supplemental treatments were 1 thrugh 6 in Table 1. Treatments were: 30% natural prtein supplements with and withut mnensin, 15% natural prtein supplements with and withut mnensin and 30% prtein supplements with ne-half f the prtein equivalent frm extruded urea-grain, with and withut mnensin. Supplement was fed at a rate f lb/head/day six days per week initially and increased t 3.25 lb/head/day fr the remainder f the trial. Mnensin was fed at a calculated level f mg/head/day. The 30% and 15% natural prtein supplements served as psitive and negative cntrls, respectively. All cws were allwed t graze in a cmmn pasture and fed their respective supplement in individual stalls six mrnings per week. Feed refusals were recrded daily and minr intake adjustments were made by peridically prviding an extra feeding n the seventh day t equalize supplement intake acrss all treatments. Cws calved frm September 5th t February 1st, with a mean calving Animal Science Research

3 tj1 0. "'" Q ;r 3 c > cc... n' c: = c: c... m )( " c» ~. 3 c»... ::J C/I... C... 0' ::J Table l. Ingredient Makeup f Prtein Supplements Item Crude prtein, %1 Dry matter, % Crn, % Sybean meal (44%), % Grund alfalfa hay, % Sug-arcane mlasses, % Sdium phsphate, % Dicalcium phsphate, % Sdium sulfate', % Trace mineral mix, % Vitamin A palmitate' Extruded urea-grain', % Natural % Prtein surce and mnensin level, mg/head/day Natural Extruded g-rain-urea lgrude prtein as determined by Kjeldahl prcedure n dry matter basis. 'Frmulated t supply 12:I nitrl!en:sulfur rati. '22,000 IV per kl! f supplement, 'Starea 44: 4.5% misture, 46.1% prtein, 12.5% urea, 97% starch damage determined by alpha.amylase prcedure. 0.0!i 15% % , Natural %

4 date f Octber 26th. Calving cmmenced befre the trial began and was cmpleted befre the trial ended. Rumen samples were btained frm five randmly selected cws per treatment, 4Y2 hurs pst-supplement feeding, n day 84 f the trial fr vlatile fatty acid determinatins. Rumen fluid was sampled a secnd time frm eight randmly selected cws per treatment n day 98 f the trial far determinatin f certain mineral and nitrgen parameters. Cws n da')' 98 were fed supplement and allwed t graze 3Y2 hurs befre sampling. Trial 2. Seventy-six mature Herefrd cws were used in a 140-day trial. Cws were blcked by weight and expected calving date and randmly alltted t tw treatment grups with tw replicatins per treatment. Cws were placed n fur pastures and rtated amng pastures at 14-day intervals t minimize pasture and lcatin effects. The tw treatments cnsisted f supplements 7 and 8 in Table 1. Cws were fed 3.0 Ib/head/day f range cubes six days per week cnsisting f 30% natural prtein supplement with r withut added mnensin at a calculated level f mg/head/day. Rumen samples were taken n days 84 and 97 f the trial t determine the effect f mnensin n mlar prprtins f acetate, prpinate and butyrate. Rumen samples n day 84 were taken an average f 4Y2 hurs pst supplement feeding and thse n day 97 were btained immediately preceding daily supplementatin. Trial 1. Results and Discussin Cw perfrmance results are shwn in Table 2. Average daily supplement intakes were apprximately equal n all treatments. Palatability f supplements cntaining extruded urea-grain was lwer than the natural prtein supplements. There were n apparent palatability prblems with the natural prtein supplements cntaining mnensin. Cws cnsuming the 30% natural supplements, with and withut mnensin lst abut 18% less weight than cws receiving extruded ureagrain with r withut mnensin, and abut 28% less weight than cws fed the 15% natural prtein supplements, with and withut mnensin. Cws n extruded urea-grain supplements were intermediate in weight lss between cws n 30% natural and 15% natural supplements when averaged ver mnensin treatments, and calculatins suggested that the urea nitrgen frm extruded urea-grain was utilized abut 43% as well Animal Science Research

5 Table 2. Perfrmance f Cws During Winter Supplementatin in Trial 1 N. f cws Daily supplement, Ib Calving date Initial cw wt., Ib Adjusted cw wt. lss, Ib Initial cw cnditin scre' Cnditin scre change' Prtein surce and mnensin level mg/head/day Natural 30% Natural 15% Starea' 30% Oct. 27 Oct.28 Oct.23 Oct. 27 Oct.20 Oct ' 232.3' 324.3' 297.2'" 257.6' 288.9' ' -1.92' -3.69" -2.92' _2.38' -3.31' 'Extruded urea_grain t furnish 50% f ttal crude prtein equivalent.,.2.,.5'.va!ues with different superscripts are sh:nificantly different (P<.05). 'Based n a scale f I t 9, I the thinnest and 9 the fattest. sdifference in initial and final cnditin. as natural prtein. This generally agrees with previus research wrk here. Cw weight lsses were abut 3% greater with mnensin supplementatin averaged ver nitrgen levels. A difference this small suggests that mnensin had little affect n cw weight lss. Cws fed 30% natural prtein supplements lst less cnditin than cws n the ther supplements. Cnditin scre lss fllwed the rder f extruded urea-grain, 15% natural mnensin, extruded urea-grain mnensin and 15% natural supplements. A prtein surce by mnensin interactin was apparent in which mnensin depressed cnditin with extruded urea-grain but imprved cnditin with 15% natural prtein. In general, cnditin lss paralleled weight lsses. Ttal and mlar percentages f vlatile fatty acids are shwn ill Table 3. Averaged ver supplements, mnensin decreased mlar percentage f prpinate. Ttal mlar cncentratin was similar acrss all treatments and was nt influenced by prtein surce. Ruminal sdium, ptassium and nitrgen parameters are shwn in Table 3. Ttal Mlar Percentages f Vlatile Fatty Acids In Rumen Fluid f Cws In Trial 1 Item Acetate', mlar % Prpinate', mlar % Butyrate', mlar % Ttal cnc., mm/1 Prtein surce and mnensin level, mg/head/day Natural, 30% Natural, 15% Starea, 30% ' 70.14, ' 75.19' '" '" 25.45' ' 7.41' 5.97, ' 6.85, , ' ,.,.3Va!ues with different superscripts are significantly different (P<.05). 'Main effect f mnensin statistically significant (P<.005). "Main effect f mnensin statistically significant (P<.05). 58 Oklahma Agricultural Experiment Statin

6 Table 4. Ruminal Mineral and Nitrgen Parameters f Cws in Trial I Prtein surce and mnensin level, mg/head/day Natural, 30% Natural, 15% Starea, 30% 0 0 Dry matter, % '2 Ttal nitrgen, mg N/IOO/mi 58.61' Rumen ammnia, mg NIL/l 00 ml ' Nn-ammnia nitrgen, mg NPN/I00 m! Sdium, ppm Ptassium, ppm , ' ''''Va!ues with different superscripts are si!(nificantly different (P<.05). Table 4. Dry matter f ruminal cntents was higher fr mnensin supplemented cws than fr cntrl cws. Ttal nitrgen cntent f rumen fluid did nt differ cnsistently acrss prtein surces r with mnensin additin. Rumen ammnia cncentratins were higher fr cws fed extruded urea-grain and 30% natural supplements than fr cws fed 15% natural supplements. Reduced rumen ammnia cncentratins with mnensin feeding have been reprted frm ther research., Supplement treatment did nt influence nn-ammnia nitrgen r sdium in rumen fluid. Ptassium in rumen cntents was similar fr prtein supplements. Hwever, averaged ver nitrgen surces, mnensin was assciated with apprximately a 10% increase in ruminal ptassium. Ptassium represents an imprtant fractin f the rumen fluid essential in maintaining a desirable medium fr bacterial fermentatin. Previus research has shwn that ptassium is essential fr labratry cellulse digestin and maintaining a desirable misture cntent f the rumen fluid. Therefre, it is pssible that cws receiving mnensin may have an increased bacterial fermentatin efficiency as shwn by the decreased mlar percent f acetate and butyrate and increased mlar percent prpinate. The higher dry matter cntent f rumen fluid frm cws supplemented with mnensin culd als be due t increased fermentatin and slwer turnver rate f rumen cntents. The results indicate that ttal rumenal nitrgen and ruminal ptassium are strngly crrelated, again suggesting that bacterial fermentatin increases as ruminal ptassium level increases. The VFA's, ptassium, ttal nitrgen and dry matter f rumen fluid reprted here supprt the thery that mnensin causes a shift in micrbial ppulatin. Trial 2. Respnse f cws in Trial 2 was similar t that f Trial I (Table 5). Changes in weight r cnditin f cws receiving the 30% natural Animal Science Research

7 supplement were similar t thse f cws fed the 30% natural mnensin supplement. VFA samples cllected n cws prir t supplement feeding (Table 6) suggested that mnensin had little affect n mlar percent f acetate, prpinate r butyrate. When sampled 4Y2 hurs pst-supplement feeding, cws fed mnensin had lwer mlar percent acetate and butyrate and higher prpinate than cws withut mnensin, but sampled prir t supplement feeding (r 22 hurs pst-supplement feeding) n difference was apparent. Whether energy supply r amunt f residual mnensin is respnsible fr this difference is unknwn. Since rumen VFA's indicted mnensin imprved rumen fermentatin in range cws but weight lss f cws was nt benefitted, it is pssible that the rumen-fed cws cnsumed less frage. Research t answer this questin is nw in prgress. Table 5. Perfrmance f Cws During Winter Supplementatin In Trial 2 Item Mnensin, Cws, number 38 Ave. daily supplement, Ib' Ave. calving date Mar. 25 Initial cw wt., Ib Adjusted cw wt. lss, Ib Initial cw cnditin scre' 5.66 Cnditin scre change' 'Dry matter basis. 'Based n scale f I t 9. I the thinnest and 9 the fattest. 3Differencein initial and final cnditin. mg/head/day 38 Mar Table 6. Ttal Mlar Percentages f Vlatile Fatty Acids In Rumen Fluid f Cws in Trial 2 Mnensin. m~/head/day Item 0 -- Sampled 22 hr pst-supplement feeding Acetate, mlar % Prpinate, mlar % Butyrate, mlar % Ttal cne., mm/1 Sampled 4Y2 hr pst-supplement feeding Acetate, mlar % Prpinate, mlar % Butyrate, mlar % Ttal cne., mm/ ' 16.08' 7.65' "'Values with different superscripts are significantly different (P<.05) ' 25.68' 5.86' Oklahma Agricultural Experiment Statin