Reproductive Performance of the Sow Subsequent to Weaning Piglets at Birth

Eighty-eight sows at two locations were used to study the effects of removal of piglets at, or within a few hours of, birth (zero-weaning) on subsequent reproductive performance. Zero-weaning resulted in an increase in the interval from farrowing to conception, a concomitant increase in the farrowing interval, an increased incidence of cystic ovarian degeneration and a reduced conception rate as compared to control animals weaned approximately 30 days postpartum. There was no significant effect on subsequent litter size. Based on plasma progesterone analysis zero-weaned sows ovulated on the average 17.0 ± 6.6 days postpartum. Attempts to establish ovarian cyclicity 48 h postpartum were not successful in terms of sows being rebred any earlier than would be possible with a 21-day weaning system. The results indicate that zero-weaning may not result in improved sow productivity in terms of achieving a greater number of litters per sow per year.