| The objectives were to investigate if a post-breeding inflammation occurs following artificial insemination (AI) in swine, its regulation by seminal components and effects on fertility. Three hundred and sixty females were used to determine the reproductive effect of an additional late estrual or metestrual AI (late AI). Late AI caused a 20% drop in farrowing rate in parity 1 and parity 2 females (P <.05) and decreased the average litter size of females that farrowed by 1.1 pigs per litter ( P <.05). The uterine leukocyte response to AI was determined in uterine lavages from 132 gilts collected at various times following AI with seminal components. The cellular content of the lavage consisted predominately (92–99%) of polymorphonuclear neutrophilic granulocytes (PMNs). A hundred fold increase in numbers of PMNs was found 12 h post-AI. This increase in numbers of PMNs persisted for >24 h in the absence of seminal plasma (SP). Seminal plasma in an AI semen dose decreased the total number of uterine PMNs (P <.05), and when suspended with spermatozoa, accelerated the rate of uterine PMN clearance compared to baseline PMN numbers (< 12 h; P <.05). Seminal plasma appeared to protect the fertilizing ability of spermatozoa in an inflammatory environment. When a single insemination was performed 12 h following induction of an inflammatory stimulus, using killed sperm or lipopolysaccharide (LPS), farrowing rates were higher in females that were inseminated with sperm suspended in SP compared to those suspended in semen extender containing no SP (P <.05). However, in the absence of an inflammatory stimulus, farrowing rates were similar regardless of the AI medium. In vitro studies demonstrated that porcine spermatozoa activated factors chemotactic to PMNs in both blood plasma and heat inactivated blood plasma. Seminal plasma, however, was not chemotactic to PMNs. Although semen often is contaminated with various pathogens, endotoxin-free semen still attracted PMNs similar to activated blood plasma (P <.05). Post-breeding uterine inflammation appears to be an important method of uterine clearance and pre-implantation preparation if properly regulated by seminal plasma. |
