Ovulation and fertility responses for sows receiving once daily boar exposure after weaning and OvuGel® followed by a single fixed time post cervical artificial insemination

Abstract Boar exposure is used to stimulate follicle development and estrus in sows after weaning and also to improve semen uptake and sperm transport with insemination. However, the need and value of boar exposure is uncertain when ovulation induction is used. These studies were designed to determine the effect of daily boar exposure after weaning when used with ovulation induction and fixed time post-cervical artificial insemination (PCAI). In experiment 1, sows were weaned into stalls and assigned to receive 3 min of daily fenceline boar exposure (BE, n = 7) or no boar exposure (NBE, n = 8). All sows received OvuGel at 96 h after weaning and BE or NBE 30 min prior to a single PCAI 24 h after OvuGel. Ovaries were assessed daily for follicle size from weaning until ovulation. Cervical contractions were measured 30 min following BE or NBE and before PCAI, while uterine contractions were measured for 1 h following PCAI. In experiment 2, weaned sows (n = 244) were assigned by parity to receive once daily BE for 1.5 min each day or NBE. OvuGel, PCAI and ultrasound methods were performed similarly as in experiment 1. Results from experiment 1 indicated BE did not significantly influence follicle size or measures of fertility. However, BE did increase the frequency of cervical contractions (P  24 h from ovulation but not when inseminations occurred ≤24 h before ovulation. The results indicate that boar exposure for only minutes each day after weaning had beneficial effects for improving follicle development, ovulation induction, and AI timing, most notably in parity 1 sows, but had no beneficial or detrimental effects on the ability to perform PCAI.