The objective of this experiment was to determine the response by feedlot bulls to DES and zeranol when administered at a younger age (about 10 months) and a lighter weight (about 500 lb.)

Embry, L. B.

Thiex, P. J.

English

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South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeSouth Dakota Cattle Feeders Field Day Proceedingsand Research Reports, 1972 Animal Science Reports1972Feedlot Performance of Bulls and the Response toDiethylstilbestrol or ZeranolP. J. ThiexSouth Dakota State UniversityL. B. EmbrySouth Dakota State UniversityFollow this and additional works at: http://openprairie.sdstate.edu/sd_cattlefeed_1972Part of the Animal Sciences CommonsThis Report is brought to you for free and open access by the Animal Science Reports at Open PRAIRIE: Open Public Research Access InstitutionalRepository and Information Exchange. It has been accepted for inclusion in South Dakota Cattle Feeders Field Day Proceedings and Research Reports,1972 by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For moreinformation, please contact michael.biondo@sdstate.edu.Recommended CitationThiex, P. J. and Embry, L. B., "Feedlot Performance of Bulls and the Response to Diethylstilbestrol or Zeranol" (1972). South DakotaCattle Feeders Field Day Proceedings and Research Reports, 1972. Paper 7.http://openprairie.sdstate.edu/sd_cattlefeed_1972/7S outh Dako ta S tate Unive r s ity B rookings , S outh Dako ta Dep artment of Animal S c ience Agri cul tural Experiment S tation Feedl o t  Perf ormance of Bul ls and the Res pons e to Diethyl s t ilbes trol or Z erano l P .  J .  Thiex and L .  B .  Embry A . S .  Series 7 2-22 I t  has b een we l l  e s t ab l ished that bulls gain faster than he ifers in the feed­lot .  Castration reduces the rate o f  growth , but s t eers gain faster than intact heif ers and show a greater growth response to die thyl s t i lb es t r o l  (DES) . In p revious experimen t s , DES or zeran.ol app eared to have no growth s t imulat ing e f fe c t  on feed­lo t b u l ls . However ,  bulls used in the exper imen t s  had b een roughed through one winter and grazed pas ture s one season b e f o r e  being pu t in the feed l o t  at about 18 to 20 months o f  age and at weie;h t s  of about 800 lb . The obj e ct ive of this exp eriment was to determine the re sponse by f eedlot b u l ls t o  D E S  and zeranol when admin i s tered at a younger age (about 10 month s )  and a lighter we i ght ( about 5 00 lb . ) . P ro cedures The bulls used in the exper iment were prop;eny of an exner imen tal c ow herd us ed in pas ture res earch at the P as ture Res earch Center , Norheck . The anima ls we re f r om Her e f o rd cows where an A . I .  p r ogram with s emen from one He r e f o rd bull was used f o r  about 6 weeks . Year l ing Herefo rd bulls which were half-s ib s o r  f r om half - s ib s ires we re then turned wi t h  the cows wi th one bu l l  to each experimental pas ture o f  8 t o  10 cows . The calves were weaned in mid-Hovember and trucked to B rookings . They we re o f f ered a rat ion comp o sed of 3 lb . of who le oat s , 2 lb . of p r o t e in supp lement and alfalf a-b r omegrass hayl a8e to app e t i t e  unt i l  pu t on the exnerimen t ab out 3 months af ter weaning . The cattle were allotted into 8 pens of 8 eac� for 4 rep l i c a t ed tr eatmen t s . Exper imental t r ea tmen t s  were a contro l ,  36 mg . zeran o l  imri l an t , 36 mg . DES implant and 60 mg . DES imp l ant . The imp lan t s  we re adminis tered at the b e f, inning of the exp eriment and again at the same leve l s  a f t e r  4 months . Ra t ions a f t e r  reaching a full feed contained 3 lb .  alfal fa-b romegrass hay la�e , 2 lb . of a 40% p r o t e in supp l emen t an d who l e  corn grain t o  app e t i t e . The p r o t e in supp lement c on tained the fo l lowing ingre d i en t s  (%) : soyb ean mea l  ( 4 47. ) , 5 0 . 5 ;  ground c o rn grain , 2 6 . 0 ;  urea ( 2 8 1 % ) , 5 . 5 ;  ground l imes t one , 6 . 0 :  trace mineral s a l t , 6 . 0 ;  d i c a l c i um phos phate , 3 . 0  and p o t a s s ium chl or ide , 3 . 0 .  V i t am in A and E we re added to furni s h  10 , 0 0 0  and 1 00 I . U . , re s p e c t ively , ner pound of s uop le ­ment . At the beg inning o f  the exp e r imen t , the cat t le were fed 20 lb . o f  a l f a l fa­b r omegras s hayl age and 3 lb . of c o rn . The haylas;e wa s reduced b v  1 lb . per head d a i ly t o  th e 3 lb . lev e l . Corn grain wa s in creas e d  hy 1 lb . d a i l y  to fu l l  feed Prep ar e d  f o r  the S ix t e e n t h  Annua l C a t t l e  Feeders Day , October 2 7 , 1 9 7 2 . 6 8  - 2 -and then fed in amounts to be nearly consumed by the next feeding . The cattle were fed in outsid e ,  paved pens without access to shade or shelter . Feeding was once daily . The experiment was terminated after 231 days . Carcass data were obtained upon slaughter . Results Results of the experiment are summarized in table 1. Differences in rate of gain , feed intake and feed efficiency between treatment groups were small . The small differences in weight gains at the end of the experiment appeared to result from some apparent growth stimulation during the first and second months of the experiment . After 2 months on the experiment , there was a 7 and 10% advantage for zeranol and 60 mg . of DES .  An advantage of this magnitude was obtained with the 36 mg . level of DES only during the first month of the experiment . These advantages in weight gains gradually became smaller during the course of the experiment . Differences in carcass characteristics measured were small in most instances . It would , therefore , appear that the treatments at the levels used had no important effects on the carcass characteristics measured . There did appear to be a slight reduction in amount of marbling for all implanted groups and a lighter color of the meat in comparison to the control group . Summary Results of this experiment with bull calves (500 lb . )  are in agreement with previous studies with yearling bulls ( 800 lb . initially) which showed little or no i�provement in feedlot performance when implanted with zeranol or DES . A level of 60  mg . of DES administered initially and after 4 months offered no advantage over 36 mg . during the 231-day experiment . Age appeared to be a factor affecting the response to these compounds . While there was a greater growth rate for about 2 months when the bull calves were implanted with zeranol or DES , this effect was largely overcome by the end of the experiment . Implanted bulls tended to have less marbling and lighter color of lean . Other carcass characteristics measured were about the same for implanted and control bulls . 6 9  - 3 -Table 1 .  Response of Feedlot Bulls to DES or Zeranol February 2 5 , 19 71-0ctober 1 3 ,  19 71--231 Days Number of animals InU . �hrunk wt . , lb . Final shrunk wt . ,  lb . Avg .  daily gain , lb . Avg . daily feed , lb . Corn grain Haylage Supplement Total Feed/100 lb . gain , lb . Corn grain Haylage Supplement Total Dres s ing percent Conformation a Marb lingb Carcass gradea MaturityC Colord Firmne s se Kidney fat , % Fat thickness , in . Loin eye area , s q .  in . Control 16 49 3 1164 2 . 90 16 . 5  3 . 5  2 . 0  22 . 0  568 122 68 758  62 . 3  20 . 8  4 . 6 20 . 2  22 . 5  4 . 2  5 . 4  3 . 0  0 . 65 12 . 02 Zeranol 36 mg. 16 494 1179 2 . 9 6 16 . 4  3 . 5  2 . 0  21 . 9  553  119 66 738 62 . 9  20 . 9  3 . 9  20 . 0  22 . 1  3 . 2  4 . 8  2 . 8  0 . 6 3 12 . 52 a Good = 17 ; Choice = 20 . Graded to one-third grade . b S light = 4 ;  small = 5 ;  modest = 6 . c A+ maturity = 22 ; A maturity s 23 . d Cherry red = 4 ;  light cherry red = 5 .  e Moderately firm = 5 ;  firm = 6 . 70  DES 3 6 mg. 15 502 1180 2 . 9 3 16 . 2 3 . 5 2 . 0  21 . 7 5 52 120 67 739 62 . 8  21 . 0  3 . 3  19 . 8  22 . 0  3 . 1  4 . 9  2 . 7  0 . 64 11 . 74 DES 60 mg. 15 501 1183 2 . 9 5  16 . 9  3 . 5  2 . 0  22 . 4  571 118 6 7 756 63 . 1  21 . 0  3 . 8  20 . 0  22 . 0  4 . 0  5 . 4  2 . 8  0 . 65 12 . 27 

Feedlot Performance of Bulls and the Response to Diethylstilbestrol or Zeranol

https://openprairie.sdstate.edu/cgi/viewcontent.cgi?article=1007&context=sd_cattlefeed_1972

Feedlot Performance of Bulls and the Response to Diethylstilbestrol or Zeranol

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