SUPEROVULATORY RESPONSES IN DIFFERENT CROSSES OF COWS TREATED WITH PREGNANT MARE SERUM GONADOTROPIN ON DIFFERENT DAYS OF CYCLE

The superovulatory response to the PMSG injection on different days of the estrous cycle was evaluated from the number of corpus luteum (CL) palpated, large follicles (greater than or equal to 10 mm diameter), ova/embryos and transferable embryos in crossbred cows. Each cow recei ved an intra muscular (i/m) injection of 2000 IU pregnant mare serum g onadotrophin (PMSG) on either day 9 (group 1), day 10 (group 2), day 1 1 (group 3) or day 12 (group 4) of the estrous cycle, followed by 3.75 mg luprostiol through intravulvo-submucosal route (IVSM) ipsilateral to the CL, 48 hr later. Ova and embryos were not affected significantl y by the day of the cycle on which PMSG was administered. Mean numbers of total ova\embryos and fertilized eggs were higher in group 2 than in group 1 with groups 4, 3 being intermediate. The average numbers of transferable embryos were highest in group 3. However, differences am ong means were nonsignificant. It is concluded that the ovarian respon se, embryo production and transferable embryos were uniform in crossbr ed cows when PMSG was administered between days 9 and 12 of the estrou s cycle.