Evaluation of out-of-season estrus induction protocols in progesterone-primed mix-breed dairy goats using eCG, GnRH and E2

Abstract

Different out-of-season estrus induction protocols were evaluated using a single progesterone (P4) priming 24h prior the use of eCG, GnRH or E2. Adult anestrus mix-breed dairy goats (n=32) were P4-primed (20 mg i.m.) and randomly assigned (n=8) to: a). E2: 1mg i.m. estradiol+0.2ml cloprostenol 24h later, b). E2+GnRH: E2+2.5ml GnRH 24h later, c). E2+eCG, E2+100 IU i.m. eCG 24h later, and d). eCG, 250IU i.m. eCG . Response variables considered the percentages of estrus (ES%, detected by sexually active males), ovulation (OV%), and pregnancy (PR%, diagnosed 45d after estrus detection). All treatments achieved high ES% (>87%) and OV% (>50%), yet, E2+GnRH reached 88% of OV% and PR%. E2 alone had the lowest PR% (p>0.05; 12.5%) and the highest interval from estrus to ovulation. The largest PR% (p>0.05; 81.5%, average) were observed in E2+GnRH and E2+eCG. Results indicate the feasibility of a simple synchronization protocol based in a single i.m. progesterone-priming plus E2+GnRH.