The Effect of Spermatozoa and Seminal Plasma on Leukocyte Migration into the Uterus of Gilts

Yorkshire × Landrace gilts were used to determine the effect of spermatozoa and seminal plasma on postbreeding uterine leukocyte influx. Estrus detection was performed with a boar at 12-h intervals following synchronization with 400 IU eCG and 200 IU of hCG. All gilts were AI once, 24 h after the detection of estrus following random assignment to a 2 × 2 × 3 factorial arrangement of treatments (sperm or sperm-free AI doses), AI dose medium (seminal plasma or PBS), and lavage time following AI. Gilts were treated with sperm (5 × 10⁹ spermatozoa; SPZ; n = 30) or sperm-free (SF; n = 30) doses containing either 100 mL of seminal plasma (SP; n = 15/treatment) or PBS (n = 15/treatment). Uterine lavage was performed once on each gilt (n = 20/time) at one of three times after AI (6, 12, or 36 h) to determine the total number of uterine leukocytes. The leukocytes consisted predominately (92 to 99%) of polymorphonuclear neutrophilic granulocytes (PMN). There was an AI × medium interaction on uterine PMN numbers. The number of uterine PMN recovered from gilts inseminated with sperm suspended in PBS was greater than the number of PMN recovered from the uterine lumen of gilts inseminated with sperm in SP, SP alone, or PBS alone (P < .05). Furthermore, SP accelerated the rate of uterine clearance when suspended with sperm cells during the first 36 h following AI (P < .05). These results indicate that seminal plasma suppresses PMN migration into the uterus following breeding and enhances the rate of disappearance of uterine inflammation.