By TIM ALEXANDER

Illinois Correspondent

URBANA, Ill. — As 11 states and some large pork producers, responding to consumer demand, move away from swine gestation crates, a new study confirms producers’ perception that group housing can adversely affect reproductive performance.

However, hurdles to maximum reproduction can be overcome with proper management, according to a University of Illinois animal health expert and a respected Illinois pork producer who did not contribute to the study.

“Reproductive performance has always been a metric that people have been concerned with about housing,” said Janeen Salak-Johnson, U of I associate professor in the Department of Animal Sciences.

She noted most previous research suggests approximate reproductive performance in group housing versus individual stalls, although most producers report diminished reproduction in group environments. Sows are often placed in group housing after pregnancy, where adverse effects can include low birth weight piglets or fewer piglets, rather than an impaired ability to attain or sustain pregnancy, Johnson concluded.

“That’s one of the big reasons people don’t see effects of group housing on reproductive success – the sows are already pregnant,” she explained. “But that doesn’t mean there aren’t potential effects on the litter during the course of pregnancy.”

Johnson’s research suggests that differences in housing design, size, feeding system and animal population can have a major impact on stress levels affecting reproductive performance. Social rank and feed intake could be the biggest stressors affecting swine reproductive performance in group housing, according to the animal welfare expert.

“If dominant sows are not able to assert their dominance during feeding by displacing submissive individuals, they get frustrated,” she said. “That can lead to low birth weight piglets. Short feeding stalls offer some level of protection, but also allow dominant sows to exhibit normal behavior.”

In an article published by Johnson, she recommends grouping sows according to individual characteristics. “Maybe we start grouping them by body weight, parity or speed of feed intake. Heavier sows eat much faster. Maybe put them all together,” she said.

“You’re still going to have a dominant sow and a submissive sow, but if you bring your composite groups closer together, I think you have an opportunity to do a better job in reducing this variation that occurs in group housing.”

Livestock producer Tim Maiers, founder of Maiers Ag Consulting in west-central Illinois, agrees with Johnson’s assessment of factors affecting swine reproduction in group environments.

“Gestation housing is something we have looked at as an industry for many years,” said Maiers, who has held leadership roles with the Illinois Pork Producers Assoc. “Whether stalls or group housing, both have their advantages and disadvantages, and both systems can work for a producer. It comes down to how producers manage those advantages or disadvantages.”

Social rank plays a major role in feed intake among gestating sows, and finding the right balance can make the difference in providing the production level producers are seeking, he explained. Sow aggression can be strongest when pregnant animals are initially introduced in group settings.

“When you mix sows, there is going to be some fighting when establishing their status in that pen. The timing of when to mix them is (important), and so is the feeding system,” he added.

New, electronic feeding systems can mitigate competition and stress. “With their ID tag, they get a certain amount of feed, and no other sow can bother them or their feed. This lessens aggression during feeding time. The feed is specified for body condition and rate of pregnancy.”

For producers without electronic, animal-specific feeding systems, Maiers agrees that Johnson’s recommendation to basically hand-select sows for open housing placement can be beneficial. “The less variety in age and body type, and the way they eat, can make for a more consistent group and hopefully cut down on some of that aggression,” he said.

“I don’t think there is one magic answer, but rather a combination of things depending on the producer’s experience. Giving them new ideas to consider, I think, is an important part of (Johnson’s) research and gives producers new information to improve their farms and the condition and welfare of their pigs.”

In addition to raising pigs with his uncle, Maiers is active in cow-calf production. In his business role with Maiers Ag Consulting, he is working with the Illinois Livestock Development Group to promote and expand the industry. He is also working with a new coalition of Illinois farm groups who are educating producers about EPA regulations for large livestock barns.

Johnson’s article, “Social Status and Housing Factors Affect Reproductive Performance of Pregnant Sows in Groups,” is published in Molecular Reproduction and Development. It was supported by a National Pork Board grant.