Reproductive response of synchronized and extensively grazed Blackbelly ewes during the summer in the tropics

Abstract

The present experiment aimed to evaluate the reproductive response of Blackbelly ewes synchronized with low doses of eCG during the summer in a tropical climate. Sixty multiparous hair ewes were divided into three groups (20 ewes/group): control group (CG; 0 IU of eCG), treated group 1 (TG-1; 140 IU of eCG) and treated group 2 (TG-2; 300 IU of eCG). The study found that the three groups of ewes showed differences in their reproductive behavior (P < 0.01). Indeed, all the ewes in the TG-1 and TG-2 groups presented a higher response to estrus than the CG (P < 0.01). In the same way, TG-1 and TG-2 had an onset to estrus in less time (P < 0.01).  On the other hand, prolificacy was also higher in TG-1 and TG-2 (P < 0.05). Likewise, ewes from TG-1 and TG-2 had more lambs than those from CG (P < 0.05). On the other hand, the variables of fertility and gestation length were similar regardless of the group of ewes (P > 0.05). It´s concluded that the ewes treated with eCG presented good reproductive behavior, and the majority did so in the first 24 to 36 h after removing the intravaginal device.