Effect of administration of prostaglandin F2 alpha on embryo recovery from the uterus on day 5 after ovulation in mares

Ten mares were used to investigate the effect of administration of prostaglandin F2 alpha on uterine tubal motility, as reflected by embryo recovery from the uterus 5 days after ovulation (day 0). Mares were assigned to 3 groups: group A, uterine flush for embryo recovery on day 7; group B, uterine flush for embryo recovery on day 5; and group C, uterine flush for embryo recovery on day 5, after treatment with prostaglandin F2 alpha (10 mg, IM) on day 3. Each mare was assigned to each group once. Embryo recovery rates for the 3 groups were: A, 6 of 10; B, 2 of 8; and C, 0 of 10. The embryo recovery rate for group C was significantly lower (P less than 0.01) than that for group A. Embryo recovery rate for group B was not significantly different from group A or group C. Administration of prostaglandin on day 3 did not increase embryo recovery rate from the uterus on day 5. Additionally, the 25% embryo recovery rate (2 of 8) for group B mares suggested an earlier time for entry of the embryo into the uterus than has previously been reported.