FSH or FSH plus LH superovulation in ewes following estrus synchronization with medoxyprogesterone acetate pessaries.

The estrous cycles of 28 ewes 9 to 10 months of age were synchronized with Medoxyprogesterone (MAP) pessaries. Superovulation was attempted by injecting either (follicle stimulating hormone) FSH or FSH plus Luteinizing Hormone (LH). MAP pessaries were in place for 12 days. FSH was administered (IM) to all ewes at 12-hr intervals over a 3-day period, 5 mg injected twice on day 11 after pessary insertion, followed by 4 and 3 mg twice daily on days 12 and 13, respectively. LH (25 mg injected IV) was given to 14 ewes within 8 hr after the onset of behavioral estrus. All ewes were hand mated with several rams at 12-hr intervals from the onset to the end of behavioral estrus. Ovulation, embryo recovery and fertilization rates were recorded for each ewe. Of 14 ewes injected with only FSH, 13 ovulated, with a mean ovulation rate of 8.2 +/- 5.6; embryo recovery rate averaged 62%, and fertilization rate was 97%. All 14 ewes given both FSH + LH ovulated, with an ovulation rate of 8.9 +/- 5.8 per ewe; embryo recovery averaged 70%, and 91% of all embryos recovered were fertilized. No statistical differences in ovulation, embryo recovery or fertilization rates were found between the FSH and FSH + LH superovulation treatment groups. In addition, no difference in the number of ewes showing estrus or duration of behavioral estrus was noted between FSH and FSH + LH treatments.