Effect of using vasectomised boars for additional matings on sow reproductive performance

Extract

Vasectomised boars are already in use on some commercial farms for detecting and synchronising oestrus, especially in gilts. Increasing the number of matings a sow receives during oestrus has been found to increase subsequent litter size and conception rate (Reed 1982, Tilton and Cole 1982). If vaginal-uterine stimulation is the underlying cause for this reproductive improvement, then similar effects should be possible using vasectomised boars.

A total of 200 Large White/Landrace cross sows were weaned at 4 to 5 weeks and housed adjacent to mature fertile boar where physical contact was possible through a barred gate. The sows were inspected for signs of oestrus each morning and, if receptive, were given a single mating with a fertile boar. Approximately 3 hours later, alternate sows were penned with a vasectomised boar and one service was supervised. These sows remained with the vasectomised boar overnight and were then remated with the original boar. The control sows were also remated with a fertile boar, 24 hours after the first service.

From weaning to service all sows were offered 2.7 kg of a 155 g/kg crude protein, barley based sow nut. After service this was reduced to 2.2 kg per day.