Attempts to Induce Fertility in Postpartum Sows

Abstract

Follicular development and ovulation were induced in sows at similar times postpartum either by gonadotropin injection or by removal of the pigs (36 sows). Intramuscular injections of FSH beginning at 6 or 21 days postpartum, were given for 3 days followed on the fifth day by an IV injection of bovine pituitary extract. Pigs were removed from control sows either at birth or at 21 days postpartum. Gonadotropin injections induced greater follicular development in sows beginning at 21 days of lactation than at 6 days. No fertilized ova were recovered from these gonadotropin-treated sows. Sows from which pigs were removed early in lactation had a longer interval to fertile estrus and a higher incidence of abnormal estrus than sows from which pigs were removed later in lactation. Fertilized ova were recovered from sows exhibiting a normal estrus. A second experiment with all sows(14) gonadotropin treated during the first 5 days postpartum compared suckled sows with those from which pigs were removed. Suckled sows tended to have a greater number of ovulations and a higher percentage of ovarian structures that were corpora lutea than sows from which pigs were removed. No recovered ova were fertilized. Forty-two primiparous sows were used in a third experiment. The results of experiment I were confirmed except that a few of the recovered ova were fertilized. Other groups of sows, both gonadotropin-treated and with pigs removed, were used to study sperm transport and the effects on fertility of oviduct insemination. Sperm were found to be transported a shorter distance in gonadotropin-treated sows than in estrual sows. Insemination into the oviduct yielded fertilized ova from control estrual sows, but not from gonadotropin treated sows. Sows from which pigs were removed at birth tended to exhibit cystic ovaries and persistent estrus. Ovulation was induced by an injection of bovine pituitary extract and fertilized ova were recovered. Copyright © 1969. American Society of Animal Science. Copyright 1969 by American Society of Animal Science