The importance of seminal plasma on the fertility of subsequent artificial inseminations in swine

Yorkshire x Landrace sows and gilts were used in a 3 × 2 factorial arrangement of treatments to determine the effect of uterine inflammation induced by either killed spermatozoa (KS) or bacterial lipopoly-saccharide (LPS) on the fertility of a subsequent, optimally timed AI. Estrus was detected with a mature boar twice daily. Twelve hours after the first detection of estrus, females received intrauterine infusions of an inflammatory stimulus consisting of a 100-mL dose of extender containing 3 × 10⁹ KS (n = 40), 20 μg of LPS (n = 40; positive control) or extender alone (n = 40; negative control). An insemination was performed 12 to 18 h later with 3 × 10⁹ motile spermatozoa (i.e., fertile AI) suspended in either 100 mL of seminal plasma (SP; n = 60) or extender replenished with of estrogens (5 μg of estradiol-17β, 4.5 μg of estrone sulfate, and 2 μg of estrone; n= 60). Transcutaneous ultrasound was performed at the time of fertile AI and again 24 h later to detect the presence or absence of preovulatory follicles. A fertile AI performed within 24 h before ovulation was considered optimal. Conception (CR) and farrowing rates (FR) were greater in females that received a fertile AI diluted with SP compared with extender (P < .01), and there was a significant (P < .05) treatment x fertile AI dilution medium interaction for both CR and FR. Females that received a fertile AI 12 h after infusion of extender had similar CR and FR regardless of fertile AI dilution medium. After inducing an inflammatory response with either KS or LPS, CR and FR were higher in females that received a fertile AI diluted with SP compared with fertile AI dilution with extender (P < .05). The effects of treatment and AI dilution media and their interactions were not significant for litter size in females that farrowed. These results show that the fertility of a subsequent AI can be impaired when semen is deposited into an inflamed environment created by an earlier AI, and this impairment was offset by inclusion of SP in the subsequent insemination.