Abstract
This study was conducted to study reproductive performance of Barki ewes subjected to three estrous synchronization programs in field conditions during breeding season. For this purpose, 36 cycling ewes were divided into 4 groups according to the program assigned: Group SeCG (n=10): ewes received intravaginal progesterone sponge (loaded with 40 mg Flugestone acetate, Chrono-gest®- Intervet International) for 7 days. At time of sponge removal, each ewe received i.m injection of 500 IU eCG (Folligon®, Intervet International); Group PG (n=10): ewes received double injections of 250μg Cloprostenol (PGF2α analogue, Estrumate®, Intervet International) with 11 days interval; Group GPG: this group included 6 ewes, on day 0 each animal received 4μg Buserelin by i.m injection (GnRH analogue- Receptal®, Intervet International), on day 7 they received 250μg Cloprostenol and 4μg Buserelin by i.m injection; Group C: 10 ewes served as control group that did not receive any treatment. Results showed that estrus induction rate was highest in SeCG group that was recorded at 100%, while it was 90%, 60%, and 50% for PG, C and GPG respectively. Estrus synchrony was more uniform in SeCG group as 70% of ewes exhibited estrus after 24 hrs from end of treatment, while 66.7% ewes in GPG group showed signs of estrus after 36 hrs from end of treatment. Conception rate was highest in GPG group that was recorded at 100%, while it was 90%, 88.9%, and 83.3% for SeCG, PG, and C respectively. Conclusion, from results we conclude that intravaginal progesterone sponge+500 IU eCG (SeCG) protocol is convenient for estrous synchronization of ewes in field conditions during breeding season with acceptable estrus induction and conception rates.

Key words: estrous synchronization, progestagen sponge, breeding season