Repeated acute activation of the hypothalamo-pituitary adrenal axis prior to and during estrus did not affect reproductive performance in gilts

We investigated the effects of repeated acute activation of the hypothalamo-pituitary adrenal axis, prior to and during estrus, on reproduction in gilts. Individual gilts (n = 24 per treatment) either served as controls or were subjected to daily acute stress ("negative handling," brief electric shock with a battery-operated prodder during confinement with the experimenter) commencing, on average, 8 days prior to estrus. Gilts subjected to negative handling had a significant elevation in plasma concentrations of cortisol that lasted at least 3-4 h, and these gilts were slower than control gilts to approach and interact with the experimenter in a standard test. Nevertheless, reproductive performance--as measured by sexual receptivity and proceptivity, ovulation, the percentage of gilts that became pregnant, the number of embryos 20-21 days after insemination, and the weight of embryos--was not affected by repeated acute activation of the hypothalamo-pituitary adrenal axis. Our results suggest that repeated acute activation of the hypothalamo-pituitary adrenal axis prior to and during estrus does not affect the factors that control estrus and ovulation in gilts.