Studies of embryo transfer in swine, 1: The effects of repeated surgical embryo recovery from same donors upon the ovarian functions and the embryo recoveries

More than 4 times of repeated surgical embryo recoveries were performed on total of 28 embryo donors. Nine donors were treated 4 times for embryo recovery, 8 donors were treated 5 times, 4 donors were treated 6 times, 3 donors were treated 7 times, one donor was treated 8 times, one donor was treated 12 times and 2 donors were treated 16 times. Nine donors were surgically operated for recovery of embryo by natural ovulation. For these animals, ovarian performances did not vary across trials within the same donor, but it varied across donors. When embryo recovery was performed at three weeks interval, it did not affect ovarian functions. The shortest interval was 12 days. Even in this case, we observed normal embryos and normal ovulation. Nineteen of 28 donors were treated for embryo recovery in natural and PMSG-treated ovulation. Effects of PMSG treatment on ovarian performances were investigated in single PMSG treatments (13 head), continual PMSG treatments (4 head) and intermittent PMSG treatments. Some of the donors showed significant increase or decrease in the ovulation rate, but other donors showed no specific tendencies in the number of ovulation. PMSG treatments did not affect ovarian performances or embryo recovery.