Comparison of Pregnancy Rates after Short - Term and Long -Term Synchronization Protocol in Ewes- Pilot Study

Abstract

The objective of the study was to compare the pregnancy rates after short-term and long-term synchroniza-tion protocol in Kivircik ewes. Ewes (n=54) were randomly divided into two synchronization groups as ST (short-term; n=27) or LT (long-term, n=27). Intravaginal sponge was inserted on the same day (D0) in both groups. It was removed at 7 days (D7) in the ST group and 13 days (D13) in the LT group. All ewes received 450 IU eCG and 75 μg d-cloprostenol at the time of sponge removal. The characteristics of vaginal discharge were evaluated following sponge withdrawal. For both protocols, 5 fertile rams per 27 ewes were used for natural mating following sponge removal. The overall estrous response and pregnancy rate were 88.9% and 64.8%, respectively. Following the synchronization, the overall estrous response (94.7% vs. 85.7%, respectively) and pregnancy rate (63.1% vs. 65.7%, respectively) were similar in both multiparous and nulliparous ewes. Although the short-term protocol reduced the rate of severe vaginitis from 48.1% to 25.9%, pregnancy rates were not different in both synchronization protocols. Nulliparous ewes had a higher rate (48.6% vs. 15.8%) of severe vaginal discharge than multiparous ewes. However, the alteration of the vagi-nal discharge severity depending on parity did not affect the overall pregnancy rate after the short-term (66.7%) and long-term (63.0%) protocols. Therefore, the long-term and short-term protocol can be used in both nulliparous and multiparous ewes in small flocks.