According to a study carried out by the University of Adelaide, piglets can be weaned later with no negative effects on sow birthing frequency. The results have also been published in the Animal Reproduction Science journal.
"Sows don't usually start their oestrous cycles again during lactation, only coming on heat after their piglets have been weaned," says Ms Alice Weaver, PhD candidate with the School of Animal and Veterinary Sciences.
"In commercial pig production, this has meant the reduction of piglet weaning ages in order to maximise the number of litters a sow can produce each year.
"Unfortunately piglets weaned early often don't thrive, with reduced growth and diarrhoea common."
Ms Weaver's study investigated whether oestrus 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 cross 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 oestrus regardless of whether they were still suckling a litter or not," says Ms Weaver.
"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."
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 the Pork CRC which is based at the Roseworthy campus.