O\u27Connell, James J.

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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, 1973 Animal Science Reports1973Growth Stimulant Substitutes for StilbestrolJames J. O'ConnellSouth Dakota State UniversityFollow this and additional works at: http://openprairie.sdstate.edu/sd_cattlefeed_1973Part 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,1973 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 CitationO'Connell, James J., "Growth Stimulant Substitutes for Stilbestrol" (1973). South Dakota Cattle Feeders Field Day Proceedings andResearch Reports, 1973. Paper 12.http://openprairie.sdstate.edu/sd_cattlefeed_1973/12South Dakota State University Brookings , South Dakota Department of Animal S cience Extension Service Growth Stimulant Substi tutes for S t ilbestro l  James J ,  O ' Connell Extension Livestock Specialist-Beef In 1 9 5 4  stilbestrol was first approved as a growth-promoting drug and became an accep ted standard . Probably no other drug has had such an e ffect on the lives tock industry as stilbestro l .  As many as 85% o f  fed cat tle have been receiving stilb es trol in some form, saving producers $ 7  to $ 1 4 p er animal in produc t ion costs . Its reasonab le cos t  and convenience overshadowed other materials available . As of  January 1 ,  1 9 73 , oral feeding of s ti lbestro l  was no longer allowed and later in the year the imp lant was banne d .  This legis lative action lef t  cattle p roducers looking for available subs titutes and fortunate ly there has been considerable research on other growth promoting drugs whi ch are alternatives to stilbes tro l .  Here are the c onnnon growth p romot ing drugs that are approved . RALGRO IMPLANTS Ralgro ( zeranol) is a growth s t imulat ing imp lant whi ch avoids many o f  the common obj ections since it does not contain a hormone . Ralgro is made from an extract of corn mold and can be used for both steers and heifers . S ince there is no hormone activi ty ,  there are none of the side effects that sometimes occur with other imp lants .  Gain response and e fficiency from Ralgro have been about equal to that of stilbestro l .  Ralgro implants apparently last for at leas t 100 days . Implanting once at the beginning of the finishing period should be suf f icient.  The level approved for s teers and heifers is 3 6  mg . ( three pellets) . The withdrawal time is 65 days be tween implanting and slaughter , which means a feeder can' t imp lant j ust 65 days before slaughter time . With growing calves they should b e  imp lanted at the beginning o f  the feeding period ( 36 mg . )  and reimp lanted with 36 mg. at the beginning o f  the finishing period .  For nursing calves the level of imp lant is also 36 mg . · Implants are p laced in the ear the same as stilbestro l .  The same imp lant machine can be used as the pellets are the same si ze . The cost of  the Ralgro pellets will be higher than stilbes tro l  running at approximately 70 cents per treatment . A sununary o f  the presentation given at Cattle Feeders Day , November 2 ,  1 9 7 3 . 6 2  - 2 -SYNOVEX IMPLANTS S ynovex is a hormone imp lant whi ch comes in two preparat ions , one type for heif ers and the other for s teers . Synovex-H for heifers contains the hormones tes tos terone and estradio l .  Synovex-S for steers contains the hormones proges terone and estradiol . 'Ibe hormone preparat ions are contained in sma ll pellets wh i ch are imp lanted in the ear . One cap sule contains the proper number of pellets for an animal .  Generally , research has shown that response to Synovex in weight gains and feed e f f i ciency is equal to , or perhaps slightly greater than , resp onse to s t ilbes trol imp lants . 'Ibe imp lants last about 150 days and cannot be used wi thin 60 days of s laugh ter . A producer feeding calves wo uld the refore imp lant at the s tart of the feeding program and reimp lant af ter 120 days . A p roducer feeding year ling cat t le or cattle that are to be fed 130 to 1 7 0  days would imp lant only once . Synovex imp lants cost app roximately 80 to 9 0  cents per animal . As with other imp lants , it is not recommended for breeding cat t le . MGA FOR HEIFERS Melenges trol Acetate ( MGA) is a growth promo ting drug approved as a feed additive for f inishing ma tur e heifers . Although MGA is a hormone , it  is a p roge s­terone , diff ering from the e s trogenic activity o f  stilbes trol and o the r hormone growth stimulants . For heifers whi ch have reached sexual maturity , MGA depresses heat periods and incr eases the rate of feedlot gain . Rate of gain is increased as much or more than from st ilbestrol . Boosts in feed e fficiency generally amount to around 8% . However , li t t le , if any , advantage will be seen in heifers which have not reached matur i ty . Hei fers mus t  be open for the drug to be benef icial . I t  is no t effective for s teers . S ince MGA is avai lab le only in feed form ,  its use for grazed hei fers is limited . Good resul ts depend on adeq uate consump t ion of the material in the feed . Current regulations call for a level of 0 . 25 mg . to 0 . 5  mg . per head per day in the feed . A 48-hour wi th drawal is required be fore slaughter . S ince heif ers wi ll re turn to heat af ter MGA is removed from feed , wi thdrawal for longer than 72 hours is no t recommende d .  Cos t is app roximately $ 1 . 25 to $ 1 . 50 per head for 1 40-day feeding period . Producers who do not take advantage of these growth promo ting drugs are los ing a great advantage in reducing production costs . B e  sure to follow the direct ions on the drug containers as to proper use of the drugs . 6 3  

Growth Stimulant Substitutes for Stilbestrol

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Growth Stimulant Substitutes for Stilbestrol

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