LAUSR

The present study aimed to investigate whether increasing estradiol (E2) 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: PGF2α+CIDR removal; 72 h post-CIDR removal: GnRH) or 5d CIDR-Heatsynch (d-5: CIDR + GnRH; d0: PGF2α+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 (n = 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 (p < .05) E2 concentrations, estrus induction and increasing trend (p < .08) for conception rate (57.7% vs. 43.6%) than 5d CIDR-Cosynch. The percentage of pregnant buffalo that exhibited estrus signs was greater (p < .01) in 5d CIDR-Heatsynch than 5d CIDR-Cosynch. Positive correlation (p < .01) was observed between POF and E2 concentrations; POF and CL diameter, CL diameter and P4 concentrations. Estrus response and P4 concentrations were indicators of probability of pregnancy. In conclusion, 5d CIDR-Heatsynch tended to improve conception rate. The estrus expression and P4 concentrations (d5 and 12 post-first-AI) is the indicator of probability of pregnancy in buffalo.