EVALUATION OF 2 TREATMENTS IN SUPEROVULATION OF MARES

The efficiency of superovulating mares with an enriched fraction of eq uine follicle-stimulating hormone (feFSH) and an equine pituitary extr act (EPE) with similar FSH content but differing in the LH amount was compared. Mares were randomly assigned to an feFSH (n=5) or EPE (n=5) treatment. The experimental period was of 2 successive estrous cycles, with the first cycle as the control. At Days 6 and 7 of the estrous c ycle, the mares received 250 mu g im cloprostenol. The treatments cons isted of daily injections of 25 mg feFSH or EPE beginning on Day 6 pos t ovulation. Mares were inseminated every other day until the last ovu lation was detected. When the mares in the control and treatment cycle s developed at least I or 2 greater than or equal to 35-mm follicle, r espectively, the treatment was interrupted, and a single injection of EPE (25 mg, iv) was administered to induce ovulation(s). Nonsurgical e mbryo recovery was performed 6 or 7 d after ovulation in both control and treatment cycles. The number of ovulations per mare was not signif icantly different (P>0.05) between feFSH and EPE groups, but both were higher (P<0.05) than that of the control cycle. The number of recover ed embryos per ovulation was similar (P>0.05) for control, feFSH and E PE groups. The high amount of LH presented in EPE did not affect the s uperovulatory response of the mares. Superovulatory treatments increas ed the ovulation rate of mares but did not affect the embryo recovery rate per ovulation. (C) 1998 by Elsevier Science Inc.