Presynchronization with simultaneous administration of GnRH and prostaglandin F2α (PGF2α) 7 days prior to Ovsynch improves reproductive profile in Hariana zebu cow

Abstract

This study is aimed at assessing the impact of simultaneous administration of GnRH and prostaglandin F2α (PGF2α) 7days prior to Ovsynch in Hariana cow. Two hundred cyclic cows (> 4months postpartum) were assigned to control (n = 54) and pre-OV (n = 146). As per Ovsynch protocol, buserelin acetate (10μg), cloprostenol (500μg), and buserelin acetate (10μg) were injected i.m. on days 0, 7, and 9, respectively, in cows irrespective of treatment. But in pre-OV cows, buserelin acetate (10μg) and cloprostenol (500μg) were also injected i.m. simultaneously 7days prior to initiate the Ovsynch protocol. Artificial insemination was performed between 18 and 24h after the 2nd GnRH of Ovsynch in both treatments. Ultrasonography and blood sampling for hormonal analysis were done on each day of treatment, on day of AI, and 12days post-AI. Pre-OV treatment resulted to increased (45.20% vs 29.62%; P < 0.05) pregnancy outcomes and higher (P < 0.01) ovulation rate to first GnRH of Ovsynch than control. Cows showing complete luteolysis in response to PGF2α of Ovsynch were also higher (P < 0.05) in pre-OV than control. Greater (P < 0.05) synchronization rate was recorded in pre-OV than control (86.76% and 68.75%). The circulating concentrations of estradiol on day of AI and progesterone on day 12 post-AI were higher (P < 0.01) in cows diagnosed pregnant than non-pregnant in both control and pre-OV treatment. In conclusion, simultaneous administration of GnRH and PGF2α 7days before Ovsynch improved the synchronization rate and luteal profile in terms of CL area and hence resulted in higher conception rate in Hariana zebu cow.