University of Adelaide research has shown that piglets can be weaned later with no negative effects on sow farrowing frequency.

The outcome of the study at the university's Roseworthy campus in Australia — published in the journal Animal Reproduction Science — is an important finding for pig producers. It allows improvements in piglet health and welfare without loss of production.

"Sows don't usually start their estrous cycles again during lactation, only coming on heat after their piglets have been weaned," said Alice Weaver, a doctoral candidate with the university's School of Animal & Veterinary Sciences. "In commercial pig production, this has meant the reduction of piglet weaning ages in order to maximize the number of litters a sow can produce each year. Unfortunately, piglets weaned early often don't thrive, with reduced growth and diarrhea common."

Weaver's study investigated whether estrus could be stimulated while sows were still feeding their piglets so the sows could be mated before their piglets were weaned. Her project was under the supervision of Dr. Will van Wettere, who leads a number of research projects in improving pig fertility and life expectancy of piglets.

Different treatment groups were set up among the Large White/Landrace crossbred sows, with half of the sows weaned early at day seven after birth and half at day 26. Half of each group had daily contact with boars from day seven.

"The research showed that providing sows daily contact with a mature male pig seven days after giving birth is sufficient to stimulate estrus regardless of whether they were still suckling a litter or not," Weaver said. "We've shown that piglet weaning age should be able to be increased with sows still producing the average 2.4 litters a year. This is very important to the pig industry and should lead to improvements in post-weaning growth and the welfare and survival of piglets.

"Most piglets in Australia are weaned at an average of 24 days. If we can push that out to at least 30 days, the extra time will have significant benefit for the piglets," she added.

Continuing research is looking at whether there are any negative impacts on the following litter, which would be conceived and gestating while the sow was still suckling the previous litter. The research is supported by Australia's Pork CRC, which is based at the Roseworthy campus.