Superovulation using PMSG and anti-PMSG in beef cows

THERIOGENOLOGY

SUPEROVULATION USING PMSG AND ANTI-PMSG IN BEEF COWS. I M. M. Zeitoun, A. M. Yassen, A. A. Hassan, f$. Z. Fathelbab , T. H. Wise and R. R. Maurer IDepartment of AniT Production, University of Alexandria, Alexandria, Egypt and USDA, ARS, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933. The most commonly used gonadotropin for stimulating follicular growth is Pregnant Mare Serum Gonadotropin (PMSG), but the long acting half life reduces embryo quality. An attempt was made to increase the number of transferrable embryos using PMSG and a monoclonal anti-PMSG (Intervet-America). A 3 x 2 factorial, using 149 Angus, Hereford, Angus and Hereford Crossbred cows (3-9 yr), was used to test three levels of PMSG (1500, 3000 and 6000 IU) with an equivalent dosage (+I or without (-) anti-PMSG. PMSG was injected i.m. on day 8 to 12 of the estrus cycle. Prostaglandin (500 ug; Estrumate, Mobay, Shawnee, KS) was injected 48 hr later. Cows were observed for estrus every six At onset of estrus, an equivalent dosage of anti-PMSG to the PMSG hr. dosage was injected i.v. into cows assigned to receive anti-PMSG. Twelve and 24 hr after onset of estrus, each cow was artificially inseminated. Embryos were collected nonsurgically on day 8. All COWS were ovariectomized on day 9 and ovarian structures measured and counted. Percentage of cows which showed estrus and ovulated decreased (P 10 mm follicles was decreased (P 10 mm follicles increased (P 10 mm follicles. Total ova were 3.2, 4.7 and 3.2 for 1500, 3000 and 6000 PMSG IU, respectively (P
The PMSG and the monoclonal anti-PMSG was kindly Intervet America, Inc., Millsboro, Delaware.

JANUARY

1988 VOL. 29 NO. 1

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