Estrus Synchronization Methods during the Non-Breeding Season of Ghezel Ewe Lambs

Synchronization can improve the reproductive performance of ewe lambs during the non-breeding season, though seeking a simple method can be more practical for farmers. Accordingly, the study aimed to evaluate the reproductive performance of ewe lambs during the non-breeding season using different clomiphene citrate (CC) protocols compared with progesterone sponge (PS) + equine chorionic gonadotropin (eCG) protocol. In this study, 40 Ghezel ewe lambs were divided into four randomly groups: 1) PS + eCG group: PS insertion (day 0-12) + 500 IU eCG injection on day 12; 2) PS + CC group: PS insertion (day 0-12) + oral administration of 100 mg CC/day (day 7-12); 3) CC + eCG group: oral administration of 100 mg CC/day (day 7-12) + 500 IU eCG injection on day 12; 4) CC group: oral administration of 100 mg CC/day (day 7-12). Ram introduction was done for five days. Blood samples were taken on 1, 11, 14, and 40 days, and serum levels of estradiol and progesterone were measured. Pregnancy and lambing rates were also assessed. Results indicated that pregnancy and lambing rates were the highest in PS + eCG group, while the lowest or no performance was observed in CC groups (P 0.05). Based on the overall results of the present study, the best synchronization method during the non-breeding season for ewe lambs was PS + eCG compared with the CC protocols.