INCREASED LITTER SIZE IN GILTS BY INTRAUTERINE INFUSION OF SEMINAL AND SPERM ANTIGENS BEFORE BREEDING 1'2

Summary Three experiments were conducted to evalu- ate the effect of exposure of the uterus to semen at least 3 wk before breeding on subse- quent reproductive performance. In Exp. 1, uterine exposure to semen was performed three times. At least 3 wk elapsed between each treatment. Control gilts received saline infusion. All gilts were bred by artificial insemination using semen from the same boars used for semen treatment. At farrowing, significantly more (10.35 vs 8.39) pigs/litter were produced by semen-treated gilts than controls. However, due to a disease outbreak (porcine parvovirus) during the last two-thirds of the farrowing period, live pigs born and litter size at 2 wk were not statistically different between the two groups. Gilts that farrowed were rebred and no difference in their reproductive performance for second litters was noted. For Exp. 2 and 3, a single semen treatment was given using freeze-thaw killed semen at estrus before breeding. Within both Exp. 2 and 3, semen- treated gilts had a larger average litter size, but no significant differences were detected. When data for nondiseased animals in Exp. 1 and animals in Exp. 2 and 3 were pooled, it was found that total pigs born (P<.01), live pigs born (P<.01) and live litter birth weight (P<.l) were all greater in semen-treated gilts than in controls. Thus, these results indicate that reproductive efficiency in gilts can be improved by intrauterine treatment with boar'semen before insemination to elicit conception.