Estrous Synchronization Of Pelibuey Ewes, Using Cidr And Different Doses Of Ecg

In the Pelibuey breed, the dose of equine chorionic gonadotropin (eCG) used in the estrous synchronization is not fully established. The objective of this study was to analyze the effect of two different doses of eCG included in progestagens-based estrous synchronization protocols, on the reproductive response of Pelibuey ewes. For this reason, 28 and 24 ewes during two consecutive years were submitted to a synchronization protocol. The first group (LOW) considered the use of a CIDR for a 7-day period, followed by an i.m. administration of 0.125 mg of Cloprostenol and a dose of 300 U of eCG. The second group (HIGH) received the same protocol with a modification, the use of a 400 U of eCG. To evaluate the response variables, were Fisher exact test and analysis of variance considered. There was no difference (P>0.05) between groups for the percentage of estrous ewes (92.31%), total conception rate (82.69%) and the conception rate of ewes with synchronized estrous (87.5%). Additionally, the estrous beginning (47.75 +/- 1.43 h) and prolificacy (1.86 lambs/partum) was similar between groups. In conclusion, the estrous synchronization protocols for Pelibuey ewes using CIDR for a 7-day period can use eCG in a dose of 300 U without effects on their associated reproductive performance.