Hormone and hormone-like compounds are commonly used for feedlot heifers. Effects on feedlot performance and carcass characteristics appear to vary depending on compounds used, levels administered including frequency of implanting, stage of growth and fattening, and dietary conditions. This experiment was one in a series to study the effects of melengestrol acetate (MGA) and implants of diethylstilbestrol (DES) or zeranol administered to heifers during growing and finishing or during finishing only

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 Reports1972Diethylstilbestrol, Melengestrol Acetate andZeranol During Growing and Finishing of FeedlotHeifersP. 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., "Diethylstilbestrol, Melengestrol Acetate and Zeranol During Growing and Finishing of Feedlot Heifers"(1972). South Dakota Cattle Feeders Field Day Proceedings and Research Reports, 1972. Paper 13.http://openprairie.sdstate.edu/sd_cattlefeed_1972/13South Dakota State University Brookings ,  South Dakota Department of Animal Science A. S .  Series 72-28 Agricultural Experiment Station Diethylstilbestrol , Melengestrol Acetate and Zeranol During Growing and Finishing of Feedlot Heifers P .  J .  Thiex and L .  B .  Embry Honnone and hormone-like compounds are commonly used for feedlot heifers . Effects on feedlot perfonnance and carcass characteristics appear to vary depending on compounds used , levels administered including frequency of implanting , stage of growth and fattening, and dietary conditions . This experiment was one in a series to study the effects of melengestrol acetate (MGA) and implants of diethyl­stilbestrol (DES) or zeranol administered to heifers during growing and finishing or during finishing only . Procedures Ninety-six heifers were used in this experiment . They were obtained from the experimental cow herd at the Pastu�e Research Center , Norbeck . The heifers were from Hereford cows where an A. I .  program with semen from one Hereford bull was used for approximately 6 weeks . Yearling Hereford bulls which were half­s ibs or from half-sib sires were used as cleanup bulls with one bull to each experimental pasture of 8 to 10 cows . The heifer calves were fed and managed in a s imilar manner during the nursing period . At weaning the heifers were allotted into two groups on basis of weight . Eight calves with each group were implanted with 36 mg . of DES and eight were implanted with 36 mg . zeranol . Both groups were managed alike and received a full feed of prairie hay , 2 lb . of oats and 2 lb . of a 40% protein supplement fortified with minerals , vitamin A and chlortetracycline . The heifers were fed this diet at the Pasture Research Center for a period of 108 days . At this time the heifers were shipped to Brookings . Diets were changed to 4 lb . corn grain , 2 lb . 40% protein supplement and a full feed of ground alfalfa-brome hay . They were fed this diet for another 72 days before starting the finishing phase of the experiment .  For the finishing phase o f  the experiment , the 9 6  heifers were allotted into 12 pens of 8 each . They were allotted on basis of previous pen group , implant treatment and weight . Six replicated treatments for the two phases were as follows : 1 2 3 4 5 6 Growing Control Control Control Control 36 mg . zeranol implant 36 mg . DES implant Finishing Control 36 mg . zeranol implant 36 mg . DES implant 0 . 4  mg . ·MGA daily 36 mg . zeranol implant 36 mg . DES imp lant Prepared for the Sixteenth Annual Cattle Feeders Day , October 2 7 ,  1972 . 105  - 2 -At the beginning of the finishing phase of the experiment ,  each heifer receiving 2 pounds of a corn-urea-soybean meal , 40% protein supplement fortified with vitamin A,  E ,  and minerals , 20 lb . of reconstituted alfalfa-brome haylage and 4 lb . of whole shelled corn . Each day the alfalfa-brome haylage was reduced by 1 lb . and whole shelled corn increased by 1 lb . When the level of haylage reached 3 lb . ,  it was kept constant and corn increased to a full feed . Feeding was once daily in outside , paved pens . The implanted cattle were reimplanted at the same levels after about J!:l. months . Accepted management practices were followed . Records were kept on individual rates o f  gain , feed consumption by pens and observations on effects of treatments on general appearance of the cattle . At slaughter carcasses were graded and carcass data obtained . The experiment was terminated at 162 days when the animals reached a desirable market weight and finish . Results Results for feedlot performance and carcass characteristics are shown in table 1 with percentage differences between treatment groups presented in table 2 .  Feed consumption data could not be obtained by treatment groups during the growing phase because of the allot�ment procedures .  Weight gain data is shown for each phase , and feed data shown is for the finishing phase only . Four heifers implanted with DES during the growing phase and reimplanted twice during finishing developed vaginal prolapses . Two of these had to be removed from the experiment . Data presented are for those completing the experiment .  One heifer each from the MGA and zeranol treatments also suffered from vaginal prolapses . Increases in rates of gain from the implant treatments during the growing phase were small in actual amounts . However , because of the low rates of gain , percentage improvements over average for all controls amounted to 11 . 4% for zeranol and 6 . 7% for DES .  Heifers receiving DES implants during finishing gained more than the controls . When implanted during the finishing phase only , gain was 5 . 9% more than controls with 3 . 4% lower feed requirements . The response was greater than for those implanted during both phases ( 3 . 4% for gain but with 5 . 8% higher feed requirements) . Overall gain for the two DES groups was the same but with lower feed requirements when DES was implanted only during finishing . Results obtained from zeranol implants during the finishing phase was about the same on weight gains as for DES . Those implanted only during finishing phase gained more than those implanted during both growing and finishing . While the advantage of implanting during both phases was small , it would amount to about 2 0  lb . per head over the 342 days involved .  Heifers implanted during both phases consumed more feed than controls during finishing resulted in equal feed require­ments .  On the other hand , implanting during finishing only resulted in slightly lower feed requirements .  Highest rates of gain during finishing were obtained from feeding MGA , 11 . 3% more than controls . Also , the most total improvement for both phases ( 7 . 1%)  was obtained with this group . However , feed requirements differed only slightly from heifers implanted with DES or zeranol during finishing only . 106 - 3 -Effects of treatments on carcass characteristics appear small .  Marbling appeared to be reduced by DES but improved by zeranol or MGA . Fat thickness also appeared reduced when DES or zeranol was implanted during the finishing phase only. Sunnnary DES or zeranol implants resulted in improved weight gains when administered as implants to heifers fed growing rations for gains of slightly over 1 lb . daily . More improvement over controls was obtained with zeranol (11 . 4%) than with DES ( 6 . 7%) . Similar response was obtained in rate of gain from zeranol ( 6 . 3% )  and DES ( 5 . 9%)  with 3 . 7 and 3 . 4% improvement in feed efficiency when implanted during finishing only . A smaller response was obtained from each compound when previously administered during the grcnving phase .  There was no advantage of DES during both phases in comparison to during finishing only . With zeranol ,  implanting during both growing and finishing was more beneficial in higher weight gains for both phases ( 5 . 9%) than implanting only during finishing ( 2 . 4%) . Highest weight gains were obtained with MGA--11 . 3% more than controls during finishing and 7 . 1% over both phases of the experiment . Effects of MGA on f eed efficiency during the finishing phase were about the same as with DES or zeranol . Effects of treatments on carcass characteristics were small . DES appeared to reduce marbling . S lightly less fat covering was associated with DES and zeranol implants administered only during finishing . Four of 16 heifers implanted with DES during both growing and finishing suffered from vaginal prolapses . The level may have been high ( 36 mg . ) , but this problem has been encountered with 24 mg . DES implants in previous experiments when administered during both growing and finishing . One heifer fed MGA and one implanted with zeranol also suffered from vaginal prolapse .  107 Table 1 .  Effects of Diethylstilbestrol , Zeranol and Melengestrol Acetate on Performance o f  Feedlot Heifers Growing phase Control Control Zeranol Control DES Control Finishing phase Control Zeranol Zeranol MGA DES DES Number 16 16 16 16 14 16 Initial wt . ,  lb . Wintering 355 369 362 36 1 370 359 Finishing 547 551 572 551 571 548 Final shrunk wt . ,  lb . 933 961 973  981 970 957 Avg . daily gain , lb . Wintering , 180 days 1 . 07 1 . 01 1 . 17 1 . 06 1 . 12 1 . 05 Finishing , 162 days 2 . 38 2 . 53 2 . 48 2 . 65 2 . 46 2 . 52 Total , 342 days 1 . 69 1 .  73 1. 79 1 . 81 1 .  75 1. 75 Avg . daily feed , finishing phase Corn 16 . 5 7 16 . 94 17 . 49 18 . 10 16 . 87 17 . 04 Haylage 3 . 79 3 . 81 3 . 81 3 . 82 3 . 68 3 . 80 Supplement 1 . 69 1 . 94 1 . 96 1 . 95 1 . 87 1 . 9 7 Total 22 . 32 22 . 69 2 3 . 26 23 . 87 22 . 42 22 . 81 f-' Feed/ 100 lb . gain , finishing phase of:-0 ro Corn 696 675 705 681 747 676 Haylage 159 150 153 144 162 151 Supplement 82 77 79 73 82 78 Total 937 902 937 898 991 905 Dressing percent 62 . 2  62 . 5  61 . 9  61 . 9  61 . 7 61 . 4  Conf ormationa 20 . 2  19 . 9  20 . 7  20 . 3  20 . 3  20 . 0  Marblingb 4 . 8  5 . 3  5 . 0  5 . 5  4 . 4  4 . 7  Carcass gradea 18 . 1  18 . 4  17 . 6  18 . 6  17 . 7  18 . 0  Maturityc 22 . 9  2 2 . 9 22 . 6  22 . 5  22 . 8  22 . 7  Co lord 5 . 0  5 . 1  4 . 7  s . o  4 . 8  5 . 0  Firmnesse 6 . 0  6 . 0  6 . 0  6 . 0  6 . 0  6 . 0  Kidney fat , % 3 . 20 3 . 03 3 . 03 3 . 2 8 2 . 82 2 . 90 Fat thickness ,  in . 1 . 44 1 . 25 1 . 49 1 . 51 1 . 53  1 . 2 7 Loin eye area , sq . in . 10 . 84 10 . 27 10 . 9 2  10 . 15 10 . 89 10 . 43 aGood = 17 ; Choice = 20 . Graded to one-third grade . bslight = 4 ;  small = 5 ;  modest = 6 .  cA+ maturity = 22 ; A maturity = 23 . dcherry red = 4 ;  light cherry red = 5 .  eModerately firm = 5 ;  firm = 6 .  - 5 -Table 2 .  Percentage Difference Between Treatment Groups for Feedlot Heifers DES both phases vs . control Avg . daily gain Feed consumed Feed/100 lb . gain DES finishing only vs . control Avg . daily gain Feed consumed Feed/ 100 lb . gain Zeranol both phases vs . control Avg . daily gain Feed consumed Feed/ 10 0  lb . gain Zeranol finishing only vs . control Avg . daily gain Feed consumed Feed/100 lb . gain MGA vs . control Avg . daily gain Feed consumed Feed/ 100 lb . gain Growing 4 . 7  9 . 3  109  Finishing 3 . 4  0 . 5 5 . 8  5 . 9  2 . 2  3 . 4  4 . 2  4 . 2  6 . 3  1 .  7 -3 . 7  11 . 3  6 . 9  -4 . 2  

Diethylstilbestrol, Melengestrol Acetate and Zeranol During Growing and Finishing of Feedlot Heifers

https://openprairie.sdstate.edu/cgi/viewcontent.cgi?article=1013&context=sd_cattlefeed_1972

Diethylstilbestrol, Melengestrol Acetate and Zeranol During Growing and Finishing of Feedlot Heifers

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