Hormone Treatments and Use of Calf Removal in Postpartum Beef Cows

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Abstract
Three treatments were used in an attempt to induce estrus in anestrous postpartum beef cows. Use of Syncro-Mate-B treatment which consists of a 9 day ear implant containing 6 mg of norgestomet and accompanied by an IM injection of 3 mg norgestomet and either 6 or 7 mg of estradiol valerate (EV) failed to increase the number of cows showing estrus (P>.05) when fed a restricted diet. Use of PMS (50 to 750 IU) in combination with Syncro-Mate-B treatment failed to increase the number of anestrous cows becoming pregnant by 21 days after implant removal. The use of short term calf removal (48 to 60 hr) in combination with the Syncro-Mate-B treatment (Shang Treatment) increased the number of cows detected in estrus and pregnant by 4 days and 21 days after implant removal (P<.05). Estrus was closely synchronized in cows receiving the Shang treatment, but subsequent breeding at a predetermined time in four herds resulted in a pregnancy rate that did not differ (P>.05) from that noted when cows were inseminated 12 hr after detection of estrus. Calf removal and calf return at various times relative to implant removal did not affect the number of cows showing estrus or becoming pregnant. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.