J. Anim Sci.
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J. Anim Sci. 1986. 63:343-347.
© 1986 American Society of Animal Science
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Synchronization of Estrus in Postpartum Beef Cows with Melengestrol Acetate and Prostaglandin F2{alpha}

W. E. Beal and G. A. Good1

Virginia Polytechnic Institute and State University,2, Blacksburg 24061

Abstract

At the beginning of the breeding season, most beef herds consist of a population of cyclic and anestrous postpartum cows. To be most effective and economical, an estrous synchronization method for postpartum beef cows must be capable of synchronizing estrus in cyclic cows and inducing estrus in anestrous cows. In the first of two experiments, the combination of melengestrol acetate (MGA) fed for 9 d and prostaglandin F2{alpha} (PGF2{alpha}) administered on the last day of MGA feeding synchronized estrus in cyclic cows (94%) and induced estrus in anestrous cows (66%) as effectively as combining PCF2{alpha} with a progestin implant (97 and 75%, respectively). In the second experiment, MGA treatment was necessary for 7 d prior to administering PGF2{alpha} to maximize the expression of estrus in cyclic and anestrous cows. In both experiments the proportion of cows exhibiting a synchronized estrus and the pregnancy rates tended to be higher for cows that were cyclic prior to treatment. However, the MGA-PGF2{alpha} treatments consistently induced estrus in more than 50% of the anestrous cows and approximately one-third of the cows that were anestrous prior to treatment conceived during the synchronized breeding period. The MGA-PGF2{alpha} treatment was 33 to 46% less expensive than a comparable estrous synchronization method that is approved by the U.S. Food and Drug Administration. If feeding MGA and administering PGF2{alpha} is approved, it may be the treatment of choice for synchronizing estrus in cyclic cows and inducing estrus in anestrous cows when supplemental feeding is feasible.

Footnotes

1 The authors express appreciation to R. A. Wallace and W. N. Vincel of Select Sires, Inc. for financial support and advice; S. Stromberg of KaMar, Inc. for donation of heatmount detectors; J. Chenault of Upjohn Co. for donation of Lutalyse and financial support; and R. B. Edwards and B. D. Wightman for collection of the data.

2 Dept. of Anim. Sci.




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R. Flores, M. L. Looper, D. L. Kreider, N. M. Post, and C. F. Rosenkrans Jr.
Estrous behavior and initiation of estrous cycles in postpartum Brahman-influenced cows after treatment with progesterone and prostaglandin F2{alpha}
J Anim Sci, July 1, 2006; 84(7): 1916 - 1925.
[Abstract] [Full Text] [PDF]


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Copyright © 1986 by the American Society of Animal Science.