Housing sows in enriched pens can reduce stress and have a positive impact on the development and survival rate of piglets, according to scientists.
A study by researchers in France found that sows housed in larger pens with deep bedding produce lower levels of cortisol, a stress hormone that can suppress the immune system and cause other health issues.
Pigs with lower levels of the hormone were less likely to have litters with still births, or produce litters that suffered from early mortality within first three days after birth, they discovered.
In the study, carried out by French agricultural research organization INRA, 106 cross-bred sows were split into two groups, with one group housed in a conventional system with slatted floors and 2.4 sq. m (25.8 sq. ft) of space per sow. The other group was housed in larger pens with enriched straw bedding.
At 105 days of gestation — ten days before they gave birth — all of the sows were moved to similar farrowing pens with slatted floors.
Researchers discovered that during gestation, sows housed in conventional systems had significantly greater concentrations of cortisol than sows in the enriched systems, but once they were transferred to farrowing pens, the levels of cortisol matched those of the sows in the other group.
However, the overall piglet mortality rate was greater in the conventional system, with 25.8% of piglets either still-born or dying before weaning, compared to 16.7% in the enriched system.
Helene Quesnel, one of the scientists behind the study, said that while the difference was not substantial, piglets in the conventional system tended to be smaller, have lower temperatures an hour after birth and smaller guts in relation to body weight.
They also had lower levels of glycogen in their muscle and liver, suggesting that in conventional systems piglets were slightly less developed and had lower energy reserves.
Speaking at the European Federation of Animal Science, Quesnel said the findings could have implications for management techniques in intensive pig systems.
“It’s known in intensive pig husbandry that housing and management for sows can generate maternal stress and maternal stress during gestation has negative effects on health,” she said.
High concentrations of cortisol in sows during gestation may influence development of piglets and the way their bodies make use of nutrients, giving them less chance of survival, she added.
“Body weight gain didn’t differ in the first 24 hours after birth, and colostrum was similar between the two systems, but the stress the sow experiences during gestation is linked to increased mortality.”