Effectiveness of an Induced Ovulation Regimen Based on Estrous Activity of Sows

The objective of the study was to determine the effect of ovulation induction at proestrus followed by timed inseminations based on subsequent estrous activity on the reproductive performance of sows. Beginning on day 3 post-weaning estrus was monitored via direct fence-line contact with mature boars. Sows identified in proestrus received OvuGel® (Induced; n=140) or no treatment (Control; n=338). All Induced sows received an insemination the next day. Induced sows that were not in estrus on the day following OvuGel® received a second insemination 24 h after the second insemination (n=15). Control sows were bred once each day of estrus for 2 days. All sows were bred by the same experienced technicians via post-cervical AI with pooled semen from the same boars. Conception rate (94.7±1.2 vs 94.3±2.0; p=0.66); farrowing rate (93.5±1.3 vs 93.6±2.1; p=0.84); and total number born (14.7±0.2 vs 14.9±0.3; p=0.67) were not different between Control and Induced sows, respectively. Number born alive tended to be higher (p=0.10) in Induced (13.4±0.2) than Control (13.0±0.2) sows. There were no effects of parity (p>0.39) or weaning-to-estrus interval (p>0.38) and interactions between these two variables and breeding treatments were not significant (p>0.23). These results indicate that use of pro-estrus for the timing of ovulation induction followed by adjustment of inseminations based on subsequent estrous activity can result in reproductive performance equivalent to breeding sows once each day estrus.