Aim: This study was conducted in Awassi ewes synchronized with FGA sponge in breeding season for comparison of PMSG and PGF2α administration effects on fertility parameters at the time of sponge withdrawal.

Materials and Methods: In this study, 75 Awassi ewes were used. The vaginal sponges (20 mg, FGA) were applied to ewes for 10 days. At the time of sponge withdrawal, any injection was not applied in FGA I group (n:25). Cloprostenol (125 mcg) was applied in FGA II group (n:25), and PMSG (500 IU) and Cloprostenol (125 mcg) were applied by intramuscular injection to the ewes in the FGA III group (n:25).

Results: The estrous start times were determined as 52.36±2.91, 38.53±2.53, and 31.30±1.96 hours in the FGA I, FGA II, and FGA III groups, respectively. In the FGA I, FGA II, and FGA III groups; the estrous rates, pregnancy rates, conception rates, abortion rates, the twinning rates, birth rates, and the litter size were detected as 88%, 72%, 88%; 64%, 60%, 84%; 72.7%, 83.3%, 95%; 18.75%, 33.3%, 28.6%; 12.5%, 6.6%, %28.5; 81.25%, 66.6%, 71.4%; 115.3%, 110%, and 140%, respectively. There was statistically significant difference between groups in terms of estrous start time (P<0.001), while no statistical difference was found between the other fertility parameters (P>0.05)

Conclusions: It was concluded that the sexual cycles could be solely synchronized by FGA sponges during breeding season, and the adding PGF2α and PMSG to the program during the time of sponge withdrawal did not affect on other fertility parameters except estrous start time.