Weaning, shipping, and commingling elicit physiological

Transcription

1 J Vet Intern Med 2008;22: Prenterl Selenium nd Vitmin E Supplementtion of Wened Beef Clves W.S. Swecker Jr, K.H. Hunter, R.K. Shnklin, G. Scgli, D.A. Fiske, nd J.P. Fontenot Bckground: The wening process in eef clves elicits physiologicl stress responses tht cn negtively ffect performnce nd helth. Supplementtion of vitmins nd minerls, prticulrly selenium (Se) nd vitmin E, might e wrrnted. Hypothesis: Tht prenterl dministrtion of Se or vitmin E would correct or prevent deficiencies of these nutrients in postwened eef clves during ckgrounding period (42 dys fter wening). Animls: One hundred nd forty-four wened steers ( kg) in 3 trils. Methods: One tril ws conducted with cttle on dry lot fed totl mixed rtion nd 2 trils were conducted on cttle on psture. Selenium ws dministered t 0.05 mg/kg BW (SC) nd vitmin E ws dministered t 1500 IU on dys 0 nd 28 (SC). Results: A tretment effect ttriutle to Se or vitmin E supplementtion on verge dily gin ws not detected in ny trils. Prenterl supplementtion with Se on dys 0 nd 28 resulted in higher serum Se concentrtions s compred with controls on dy 42. Prenterl supplementtion with Se on dys 0 nd 28 improved Se sttus from mrginl to dequte in 1 tril. Prenterl supplementtion with vitmin E did not improve serum vitmin E concentrtions in ny experiment. Conclusions nd Clinicl Importnce: Supplementtion with vitmin E or Se or comintion of oth did not hve significnt effect on clf performnce during the 42-dy ckgrounding period. Key words: Bckgrounding; Beef Cttle; Selenium; Vitmin E. Wening, shipping, nd commingling elicit physiologicl stress responses in clves tht my negtively ffect performnce nd helth. 1 3 Bckgrounding is loosely defined term tht refers to the 1 3 month period fter wening in which clves re mnged to minimize the stress of wening. Feeds my e ltered to prepre for the next system of the production cycle, nd immuniztions nd prsite control re dministered, if needed. Vitmins nd minerls re injected into wened clves to prevent deficiencies nd improve helth. Prenterl supplementtion provides the opportunity for individul clf tretment nd removes relince on feed intke for nutrient provision in the ckgrounding period. Vitmin E nd selenium (Se) re essentil to ovine helth ecuse deficiencies result in nutritionl myopthy or impired immune function. Both outcomes re ssocited with decresed ntioxidnt cpcity ecuse Se is essentil for the formtion of glutthione peroxidses (GPXs), which ct in cells to convert peroxides to lcohols, 4 nd vitmin E, lipid-solule ntioxidnt, scvenges rective oxygen species nd lipid hydroperoxides. 5 Se supplementtion hs een ssocited with From the VA-MD Regionl College of Veterinry Medicine (Swecker) nd Deprtment of Animl nd Poultry Sciences (Hunter, Shnklin, Scgli, Fontenot), Virgini Polytechnic Institute nd Stte University, Blcksurg, VA ; nd Shenndoh Vlley Agriculture Reserch nd Extension Center (SVAREC), Steeles Tvern, VA (Fiske). This project ws conducted t the Shenndoh Vlley Agriculture Reserch nd Extension Center (SVAREC), Steeles Tvern, VA nd Kentlnd Frms, Blcksurg, VA nd Virgini Tech, Blcksurg, VA. Corresponding uthor: W.S. Swecker Jr, VA-MD Regionl College of Veterinry Medicine, Virgini Polytechnic Institute nd Stte University, Phse II Duckpond Drive, Blcksurg, VA ; e-mil: cvmwss@vt.edu Sumitted July 2, 2007; Revised August 22, 2007; Accepted Octoer 23, Copyright r 2008 y the Americn College of Veterinry Internl Medicine /j x incresed serum ntiody titers (IgG) in growing eef cttle, thus enhncing immune response to illness. 6 8 Likewise, Se supplementtion hs improved in vitro cellulr immune responses of cttle. 9 Cttle in the southestern United Sttes re t incresed risk of Se deficiency ecuse they re rised in res with low concentrtions of Se in the soil. Cttle from the southestern United Sttes re more commonly severely or mrginlly deficient in Se (18.6 nd 23.8%, respectively) s compred with cttle from other regions. 10 Cttle producers nd veterinrins who mnge wened eef clves, especilly clves from Se-deficient regions, need informtion on effective nd prcticl supplementtion strtegies. The ojective of the present studies ws to determine if prenterl Se nd vitmin E supplementtion seprtely or in comintion would lter Se or vitmin E sttus nd enhnce performnce in wened eef clves. Mterils nd Methods Two sets of clves were used for these experiments tht were performed from Octoer to Decemer. One set of clves included wened steers orn etween Mrch nd My t the Shenndoh Vlley Agriculturl Reserch nd Extension Center (SVAREC), Steeles Tvern, VA. Steers were vccinted 3 5 weeks efore wening ginst ovine respirtory syncytil virus, infectious ovine rhinotrcheitis, ovine virl dirrhe virus, nd prinfluenz nd clostridil disese. For these steers, dy 0 of the study ws the dy the clves were wened. The other set of clves included steers purchsed from feeder clf sles in West Virgini. Purchsed steers were ssumed to e of similr ge nd wened t the time of the sle. Purchsed steers were trnsported to SVAREC or Blcksurg within 24 hours of the conclusion of the sle, nd dy 0 ws the dy the steers rrived t the testing loction. Purchsed steers were vccinted with the sme products, s the SVAREC-orn clves on dy 0. All steers were treted for internl nd externl prsites with pour-on nthelmintic c on dy 0. The uthors determined tht steers/tretment would give power to determine oth sttisticlly nd iologiclly meningful chnges in Se nd vitmin E sttus sed on previous experiments with purchsed clves from the region nd the numer of cttle used in other refereed pulictions. 6 9 Conversely, the study design lcked power to dequtely ssess

2 444 Swecker et l tretment rtes for common diseses such s ovine respirtory disese complex; thus tretment rtes re not presented. The Virgini Tech Animl Cre Committee pproved ll procedures. Steers were weighed without restriction from feed nd wter nd lood smples were collected vi jugulr venipuncture on smpling dtes. Smples for serum Se nd vitmin E were collected into sterile, no dditive, tues d nd were centrifuged t 600 g for 15 minutes nd serum ws frozen t 20 1C until nlysis. On ech smpling dy, forge smples were otined y mens of hnd-held clippers t n estimted grzing height of 2.5 cm every 15 m while wlking criss cross pttern in ech pddock. Smples were dried for 48 hours in forced drft oven t 60 1C, nd stored in cloth gs. If forge vilility ws indequte, hy ws fed to nimls nd hy smples were otined with core smpler. Design nd Tretments for Individul Studies Experiment 1 Prenterl Se or Vitmin E. Forty-eight purchsed steers (203 kg) were llotted ccording to order through the chute into 8 locks of 6 steers/lock. Steers within locks were rndomly llotted to 6 tretments rrnged in 2 3 fctoril. Steers were individully fed 2 diets d liitum: 40 : 60 nd 70 : 30 (s fed) forge : concentrte diets in dry lot (Tle 1). Steers were fed in individul stlls with hnd weighing of feed nd orts. Se nd vitmin E tretments were (1) no injection or control, (2) 0.05 mg Se/ kg BW (ody weight), e or (3) 1500 IU vitmin E. f Injections were given SC on dys 0 nd 28. Ech tretment group contined 16 steers. Experiment 2: Prenterl Se or Vitmin E. Forty-eight purchsed steers (203 kg) were llotted ccording to order through the chute into 6 locks of 8 steers/lock. Within locks, steers were llotted t rndom to 8 pddocks (0.61 h ech); 4 low-endophyte fescue nd 4 low-endophyte fescue nd lflf pddocks. Within ech pddock, the 6 steers were rndomly ssigned to 1 of 3 injection tretments: (1) no injection or control, (2) 0.05 mg Se/kg BW, e or (3) 1500 IU vitmin E. f Injections were given SC on dys 0 nd 28. Ech tretment group contined 16 steers. Steers in fescue nd lflf pddocks were given d liitum ccess to minerl locks g tht contined g poloxlene/kg to minimize lot. The lot locks contined Se. Trce minerl locks h without Se were lso plced in ll pstures. Experiment 3: Prenterl Se or Vitmin E or Comintion of Se nd Vitmin E. Forty-eight steers (254 kg) wened t SVAREC were llotted y cow system i into 12 locks of 4 steers/ lock. Within ech lock, steers were llotted t rndom to 4 fescue pddocks (1.21 h ech), nd then steers within pstures were rndomly llotted to 4 injection tretments: (1) no injection or control, Tle 1. Ingredient composition of diets fed wened eef steers fed in dry lot. Forge: Concentrte 40 : : 30 Ingredient Corn Soyen mel Grss hy Diclcium phosphte 0.1 Limestone Trce-minerlized slt Dry mtter. Zn 0.35%, Fe 0.20%, Mn 0.20%, Cu 0.03%, Co 0.005%, I 0.007%. % (2) 0.05 mg Se/kg BW, e (3) 1500 IU vitmin E, f or (4) 0.05 mg Se/kg BW e plus 1500 IU vitmin E. f Injections were given SC on dys 0 nd 28. Ech tretment group contined 12 steers. Steers remined on the pddocks for the durtion of the study nd were fed grss hy when psture forge ws limited (o1000 kg/h). Plin white slt ws plced in ll pddocks. For ll 3 experiments, steers were weighed nd smpled on dys 0, 7, 14, 28, nd 42. Chemicl Anlyses All smples of feed ingredients, experimentl diets, nd pstures were ground through 1-mm screen with Wiley mill. Crude protein ws determined vi the comustion method 11 with nitrogen nlyzer. j Neutrl detergent fier nd ADF were determined ccording to Vn Soest et l. 12 y ANKOM technology. k Forge smples were digested for minerl nlysis with 2 : 1 (v/v) HNO 2 : HClO Forge concentrtions of C, Mg, K, Cu, nd Zn were nlyzed y flme tomic sorption spectroscopy. l Serum, lood, nd forge Se concentrtions were nlyzed y tomic sorption spectroscopy nd grphite furnce. l Serum smples were nlyzed for -tocopherol ccording to the method descried y Miller nd Yng 14 nd Crig et l. 15 with n HPLC m fitted with 0.01 mm pore C18 column. Sttisticl Anlyses Serum Se nd vitmin E concentrtions were nlyzed with the mixed model n for repeted mesures. Fixed effects were prenterl tretment (Se or vitmin E tretment), dy, tretment dy, nd feed type (Experiment 1) or forge type (Experiment 2). Pddock ws rndom effect for Experiments 2 nd 3. The suject ws clf nested within tretment (Experiment 1) or tretment psture (Experiments 2 nd 3). Significnt tretment dy interctions (P o.05) were first tested with the slice option for dy. If tretment ws significnt on given dy, tretment mens were compred with Tukey s test. Covrince structure for repeted mesures ws est modeled with the heterogeneous utoregressive structure. Averge dily gin (ADG) for the ckgrounding period ws nlyzed with the mixed model. n Fixed effects were Se or vitmin E tretment, nd feed type or forge. Clf nested within tretment (Experiment 1) or tretment psture (Experiments 2 nd 3) ws the rndom effect. Significnce ws determined t P o.05. Results Forge Chemicl Composition The chemicl composition of ll diets fed nd forges grzed in ckgrounding trils is shown in Tle 2. Se concentrtions of psture forges in Experiment 3 contined less thn the NRC requirement for Se for eef cttle (0.1 mg Se/kg diet). 5 Serum Se Concentrtions In Experiment 1, the effects of Se tretment (trt) (P o.001), dy (P o.001), nd Se trt dy (P 5.001) were detected on serum Se. Steers on dry lot given Se injections on dys 0 nd 28 hd higher (P o.0001) serum Se concentrtions on dys 7, 14, 28, nd 42, compred with steers supplemented with vitmin E or control steers (Fig 1). Diet type did not influence serum Se concentrtions (P 5.79). In Experiment 2, the effects of Se tretment (P o.001), dy (P 5.006), psture type (P 5.022), Se trt dy

3 Selenium Supplementtion of Clves 445 Tle 2. trils. Chemicl composition of diets (Experiment 1) nd forges (Experiments 2 nd 3) used in ckgrounding Experiment 1 Experiment 2 Experiment 3 Item Dry lot 70 : 30 Dry lot 40 : 60 Fescue psture Fescue-lflf psture Fescue psture Grss hy CP NDF ADF C Mg K P Cu Zn Se Ech pddock ws smpled 5 times. Vlues re mens. Percent, DM sis. Prts per million, DM sis. (P 5.022), nd psture type dy (P 5.001) were detected on serum Se (Fig 2). Steers injected with Se hd higher Se concentrtions on dys 7, 28, nd 42 thn control steers or steers injected with vitmin E. Serum Se concentrtions incresed in steers on fescue-lflf pstures from 28.0 ng/ml (95% CI ) to 36.7 ng/ml (95% CI ) from dys 0 to 42, while serum Se of steers on fescue pstures decresed from 37.5 ng/ml (95% CI ) to 26.3 ng/ml (95% CI ) during the sme time period. In Experiment 3, the effects of tretment (P o.001), dy (P o.001), nd tretment dy (P o.001) were detected. Steers given Se or comintion of Se 1 vitmin E on dys 0 nd 28 hd higher serum Se concentrtions thn control steers or steers given vitmin E on dys 7, 14, nd 42 (P o.05) (Fig 3). However, tretment effect on serum Se concentrtions ws not detected on dy 28 (P 5.714). Vitmin E Sttus In Experiment 1, vitmin E injection tretment dy interction (P 5.003) ws detected (Tle 3). From dys 0 to 7, vitmin E declined in the control (P 5.007) nd Se (P 5.001) groups; however, serum vitmin E did not differ etween dys 0 nd 7 in the vitmin E group (P 5.41). In the 2 psture trils, vitmin E tretment effect on serum -tocopherol ws not detected (P nd.725 for Experiments 2 nd 3, respectively) (Tle 3). In ll trils, serum -tocopherol decresed from dys 0 to 42. Animl Performnce A tretment effect of Se or vitmin E supplementtion or oth on ADG ws not detected in ny of the experiments (Tle 4). All steers enrolled in the experiments completed the experiments Con Vit E Se Serum Se (ng/ml) 60 Adequte Mrginl Deficient Time fter supplementtion (dys) Fig 1. Serum selenium concentrtions of steers fed 40 : 60 or 70 : 30 forge: concentrte diets nd given prenterl Vitmin E or selenium. Con, Control group; n, 16; Vit E, vitmin E group IU vitmin E on dys 0 nd 28. n, 16; Se, selenium group. MuSe (5 mg Se nd 50 mg vitmin E/mL) t dose of 0.05 mg Se/kg BW on dys 0 nd 28. Vlues represent lest squre men nd error rs represent stndrd devition;, : mens within dy with different superscripts differ (P o.05).

4 446 Swecker et l Serum Se (ng/ml) Con Vit E Se Deficient Mrginl Adequte Time fter supplementtion (dys) Fig 2. Serum selenium concentrtions of steers on fescue-lflf or fescue pstures given prenterl Vitmin E or selenium. Con, Control group; n, 16; Vit E, vitmin E group IU vitmin E on dys 0 nd 28. n, 16; Se, selenium group. MuSe (5 mg Se nd 50 mg vitmin E/mL) t dose of 0.05 mg Se/kg BW on dys 0 nd 28. Vlues represent lest squre men nd error rs represent stndrd devition;, : mens within dy with different superscripts differ (P o.05). Discussion A successful Se supplementtion progrm should not only mintin Se sttus ut lso improve Se sttus from deficient or mrginl to dequte. Prenterl injection of Se on dys 0 nd 28 to steers in the present studies resulted in dequte Se sttus in 1 of the 3 experiments. Se sttus of supplemented clves in ll experiments, however, ws higher thn unsupplemented control clves. For the present study, wenlings ( dys of ge) with serum Se concentrtions of less thn 25 ng/ml re deficient nd serum Se concentrtions of ng/ml hve dequte Se sttus. 16 In the present experiments, men serum Se concentrtions on 1 group of purchsed steers were considered deficient nd the other group ws considered mrginl t the initition of the study. 16 Steers rised t SVAREC (Experiment 3) would e considered mrginl in Se sttus t the initition of the study. These series of experiments llowed for comprisons of prenterl Se supplementtion of clves with rnge in Se sttus. Prenterl Se supplementtion of Se-deficient cttle hs resulted in mixed responses in performnce. Se injection of Hereford Angus clves from Se-deficient dms within 2 dys of irth resulted in higher weight gins on dy Three dditionl Se injections on dys 70, 114, nd 149 did not influence wening weight (209 dys), ut 80 Con Vit E Se Vit E + Se Serum Se (ng/ml) Deficient Mrginl Adequte Time fter supplementtion (dys) Fig 3. Serum selenium sttus of steers on fescue psture given Vitmin E, selenium, or comintion of oth. Con, Control group; n, 12; Vit E, vitmin E group IU vitmin E on dys 0 nd 28. n, 12; Se, selenium group. MuSe (5 mg Se nd 50 mg vitmin E/mL) t dose of 0.05 mg Se/kg BW on dys 0 nd 28; n, 12, Vit E 1 Se IU vitmin E nd MuSe (5 mg Se nd 50 mg vitmin E/mL) t dose of 0.05 mg Se/kg BW on dys 0 nd 28. n Vlues represent lest squre men nd error rs represent stndrd devition;, : mens within dy with different superscripts differ (P o.05).

5 Selenium Supplementtion of Clves 447 Tle 3. Serum -tocopherol concentrtions (mg/l) of wened eef clves supplemented with selenium (Se) or vitmin E (Vit. E) or oth. Study Experimentl Group Dy None Vit. E d Se e Vit. E 1 Se f Experiment 1 dry lot ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Experiment 2 fescue, fescue-lflf ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Experiment 3 fescue c ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Dt re lest squre mens (95% confidence intervl), n 5 16/injection tretment. Dt re lest squre mens (95% confidence intervl), n 5 16/injection tretment. c Dt re lest squre mens (95% confidence intervl), n 5 12/injection tretment. d Vitmin E supplemented t 1500 IU on dys 0 nd 28. e MuSe (5 mg Se nd 50 mg vitmin E per ml) t dose of 0.05 mg Se/kg BW on dys 0 nd 28. f Comintion injection ws 1500 IU vitmin E nd 0.05 mg Se/kg BW on dys 0 nd 28. did increse lood Se t wening. There re incresed weight gins in the first 14 dys fter n IM Se injection (0.07 mg/kg) in clves with low initil Se sttus. 18 Supplementtion of steers entering the feed lot with vitmin E nd Se did not hve significnt effect on ADG or the verge numer of dys nimls were sick. 6 A difference in ADG of wened eef clves ws not detected etween Se-supplemented clves nd control clves. 7 Present results suggest no response in ADG with prenterl Se supplementtion. Results from previous studies regrding serum minerl concentrtions of stressed clves hve een inconsistent. One possile explntion for inconsistencies etween studies is tht minerl concentrtions in the niml my fluctute in response to infection, feed nd wter restrictions, shipping, wening, trnsport stress, previous clf supplementtion, or previous dm supplementtion preprtum. 19 Clves orn to cows supplemented with Se hd higher Se concentrtions thn clves orn to cows not supplemented with Se. 20 In the present set of experiments, steers from SVAREC hd numericlly higher serum nd lood Se concentrtions, respectively, thn purchsed steers; however, Se supplementtion through minerl mix ws ville efore wening. In purchsed steers (Experiments 1 nd 2), Se injections on dys 0 nd 28 resulted in higher serum Se concentrtions t the end of the tril compred with control steers, yet Se sttus would still e considered mrginl. Se injected IM t the sme dose used in the present study incresed lood nd serum Se in wened Hereford heifers for 28 dys fter injection s compred with controls, ut did not result in lood Se concentrtions or GPX ctivity tht would e considered dequte. 21 Injections in the present study were dministered SC. Perhps IM injections would hve given different results. In Experiment 2, serum Se of steers on tll fescue-lflf incresed in the 42-dy period, wheres serum Se declined in the steers on tll fescue. Forge Se concentrtions were similr; thus the increse in serum Se my e confounded y the presence of the Se-contining lot locks on the fescue-

6 448 Swecker et l Tle 4. oth. Performnce of steers supplemented with prenterl selenium (Se) or vitmin E (Vit. E) or comintion of Tril Experimentl Group Item (kg) None Vit. E d Se e Vit. E 1 Se f Experiment 1 dry lot Dy 0 weight ( ) ( ) ( ) Dy 42 weight ( ) ( ) ( ) ADG Dy ( ) ( ) ( ) Experiment 2 fescue, fescue-lflf Dy 0 weight ( ) ( ) ( ) Dy 42 weight ( ) ( ) ( ) ADG (kg) dy ( ) ( ) ( ) Experiment 3 fescue c dy 0 weight ( ) ( ) ( ) ( ) dy 42 weight ( ) ( ) ( ) ( ) ADG dy ( ) ( ) ( ) ( ) Dt re lest squre mens (95% confidence intervl), n 5 16/injection tretment. Dt re lest squre mens (95% confidence intervl), n 5 16/injection tretment. c Dt re lest squre mens (95% confidence intervl), n 5 12/injection tretment. d Vitmin E supplemented t 1500 IU on dys 0 nd 28. e MuSe (5 mg Se nd 50 mg vitmin E per ml) t dose of 0.05 mg Se/kg BW on dys 0 nd 28. f Comintion injection ws 1500 IU vitmin E nd 0.05 mg Se/kg BW on dys 0 nd 28. ADG, verge dily gin. lflf pstures. In the dry lot experiment (Experiment 1), the complete diets contined Se (0.18 ppm nd 0.14 ppm) t concentrtions higher thn NRC recommendtions; however, serum Se declined in the control group. Rndom lloction of clves efore ssessment of Se sttus my result in numericl differences etween tretment groups on dy 0, which ws oserved in 1 of the 3 experiments in the present study. All prticipnts in collection of clf smples were cogniznt to otin lood smples efore injections. However, indvertent injection of Se efore lood smple collection should e considered. Alloction of cttle to experiments fter nlysis of Se ws not fesile in these experiments. Supplementtion of vitmin E in the rtion hs een ssocited with incresed performnce nd humorl immune response of feed lot cttle. 22,23 In the present experiments, vitmin E injections were unsuccessful in enhncing serum -tocopherol over the 42-dy ckgrounding period. Numericlly, serum -tocopherol concentrtions were higher in clves ckgrounded on psture thn clves fed on dry lot. Conclusions Se injections temporrily ( 28 dys) increse serum Se concentrtions, ut did not enhnce ADG or correct the deficient stte. Becuse Se-deficient cttle my e more susceptile to disese or decresed immune function, lternte supplementtion strtegies to e considered my e perorl supplementtion, IM injection, or incresed frequency of SC injections. Vitmin E sttus, s mesured y serum -tocopherol, ws not influenced y prenterl injection. Prenterl supplementtion with Se, lone or in comintion with vitmin E, improved serum Se concentrtions ut did not hve significnt effect on clf growth rte during the 42-dy ckgrounding period. Acknowledgment This work ws funded in prt y the USDA/ARS, nd is prt of n inititive, Psture-Bsed Beef Systems for Applchi, collortion mong VA Tech, USDA- ARS, Bever, WV, West Virgini University, nd Clemson University, USA. Footnotes Pyrmid 4, Fort Dodge Animl Helth, Fort Dodge, IA Vision 7, Intervet, Boxeer, the Netherlnds c Cydectin, Fort Dodge Animl Helth d BD Vcutiner 6434, Frnklin Lkes, NJ e MuSe, Schering-Plough Animl Helth Corp, Mdison, NJ, 5 mg Se/mL nd 50 mg tocopherol/ml f Vitl E-300, Schering Plough Animl Helth, Umn, NJ g PM Ag Products, Homewood, IL (4% CP, 5% C, 4% P, 1% Mg, 0.054% Zn, Cu%, % I, nd % Co) h Crgill Inc Minnepolis, MN (38% N, 0.35% Zn, 0.2% Fe, 0.2% Mn, 0.13% Cu, 0.01% I, nd 0.01% Co)

7 Selenium Supplementtion of Clves 449 i Fontenot JP, Clphm WM, Swecker WS Jr, et l Yerround forge systems for eef cows nd clves. Proc XX Int Grsslnd Congress, Dulin, Irelnd:464 (strct) j PerkinElmer 2410, Norwlk, CT k Ankom 220, Firport, NY l PerkinElmer AAnlyst 800, Norwlk, CT m Agilent Technologies, 1100 series, Wilmington, DE n SAS, v 9.1, Cry, NC References 1. Lofgreen GP. Mss mediction in reducing shipping feverovine respirtory disese complex in highly stressed clves. J Anim Sci 1983;56: Briggs RE, Frnk GH, Purdy CW, et l. Rpid spred of unique strin of Psteurell hemolytic serotype 1 mong trnsported clves. Am J Vet Res 1998;59: Frnk GH, Briggs RE, Duff GC, et l. Effects of vccintion prior to trnsit nd dministrtion of florfenicol t time of rrivl in feedlot on the helth of trnsported clves nd detection of Mnnheimi hemolytic in nsl secretions. Am J Vet Res 2002;63: Berdnier CD. Advnced Nutrition: Micronutrients. Boc Rton, FL: CRC Press; NRC. Nutrient Requirements of Beef Cttle, 7th rev ed. Wshington, DC: Ntionl Acdemy Press; Droke EA, Loerch SC. Effects of prenterl selenium nd vitmin E on performnce, helth nd humorl immune response of steers new to the feedlot environment. J Anim Sci 1989;67: Swecker WS Jr., Eversole DE, Thtcher CD, et l. Influence of supplementl selenium on humorl immune responses in wened eef clves. Am J Vet Res 1989;50: Nicholson JWG, Bush RS, Allen JG. Antiody responses of growing eef cttle fed silge diets with nd without selenium supplementtion. Cn J Anim Sci 1993;73: Pollock JM, McNir J, Kennedy S, et l. Effects of dietry vitmin E nd selenium on in vitro cellulr immune responses in cttle. Res Vet Sci 1994;56: Drgtz DA, Ross PF. Blood selenium concentrtions in cows nd heifers on 253 cow-clf opertions in 18 sttes. J Anim Sci 1996;74: Interntionl A. Officil Methods of Anlysis of AOAC Interntionl, 17th ed. Githersurg, MD: Assocition of Anlyticl Communities; Vn Soest PJ, Roertson JB, Lewis BA. Methods for dietry fier, neutrl detergent fier, nd nonstrch polyscchrides in reltion to niml nutrition. J Diry Sci 1991;74: Muchovej RMC, Allen VG, Mrtens DC, et l. Aluminum, citric cid, nitrilotricetic cid, nd soil moisture effects on luminum nd iron concentrtions in ryegrss. Agron J (Print) 1986;78: Miller KW, Yng CS. An isocrtic high-performnce liquid chromtogrphy method for the simultneous nlysis of plsm retinol, lph-tocopherol, nd vrious crotenoids. Anl Biochem 1985;145: Crig AM, Blythe LL, Lssen ED, et l. Vritions of serum vitmin E, cholesterol, nd totl serum lipid concentrtions in horses during 72-hour period. Am J Vet Res 1989;50: Herdt TH, Rumeih W, Brselton WE. The use of lood nlyses to evlute minerl sttus in livestock. Vet Clin North Am Food Anim Prct 2000;16: Cstelln DM, Ms JP, Grdner IA, et l. Growth of suckling eef clves in response to prenterl dministrtion of selenium nd the effect of dietry protein provided to their dms. J Am Vet Med Assoc 1999;214: Reffett JK, Spers JW, Htch PA, et l. Influence of selenium nd zinc on performnce, lood constituents, nd immune response in stressed clves. Biol Trce Elem Res 1986;9: Glyen ML, Perino LJ, Duff GC. Interction of cttle helth/immunity nd nutrition. J Anim Sci 1999;77: Enjlert F, Lereton P, Slt O, et l. Effects of pre- or postprtum selenium supplementtion on selenium sttus in eef cows nd their clves. J Anim Sci 1999;77: Ms J, Peuroi JR, Tonjes T, et l. Intrmusculr selenium dministrtion in selenium-deficient cttle. J Vet Intern Med 1993;7: Secrist DS, Owens FN, Gill DR. Effects of vitmin E on performnce of feedlot cttle: A review. Prof Anim Sci 1997;13: River JD, Duff GC, Glyen ML, et l. Effects of supplementl vitmin E on performnce, helth, nd humorl immune response of eef cttle. J Anim Sci 2002;80: