5d CIDR-Heatsynch improves the circulatory estradiol levels, estrus expression and conception rate in anestrus buffalo ().

The present study aimed to investigate whether increasing estradiol (E) during preovulatory period would increase estrous expression, luteal profiles and conception rate in 5d CIDR based timed AI protocol. A total 156 anestrus buffalo allocated (78 per group) to either 5d CIDR-Cosynch (d-5: CIDR + GnRH; d0: PGF+CIDR removal; 72 h post-CIDR removal: GnRH) or 5d CIDR-Heatsynch (d-5: CIDR + GnRH; d0: PGF+CIDR removal; 24 h post-CIDR removal: estradiol benzoate) group. All the buffaloes inseminated at 72 and 84 h post-CIDR removal. A subset of buffalo ( = 58) were subjected to examination of the follicle diameter and luteal profile during protocol, post-AI on days 5 and 12. The buffalo in 5d CIDR-Heatsynch had greater ( < .05) E concentrations, estrus induction and increasing trend ( < .08) for conception rate (57.7% vs. 43.6%) than 5d CIDR-Cosynch. The percentage of pregnant buffalo that exhibited estrus signs was greater ( < .01) in 5d CIDR-Heatsynch than 5d CIDR-Cosynch. Positive correlation ( < .01) was observed between POF and E concentrations; POF and CL diameter, CL diameter and P concentrations. Estrus response and P concentrations were indicators of probability of pregnancy. In conclusion, 5d CIDR-Heatsynch tended to improve conception rate. The estrus expression and P concentrations (d5 and 12 post-first-AI) is the indicator of probability of pregnancy in buffalo.