Sows undergo changes in structure over time, according to research by Melanie Trenhaile-Grannemann, a graduate student at the University of Nebraska-Lincoln.
Her research is based on collecting videos, and still images, of sows at 17 different time points in their lives between 112 days of age and the parity 4 weaning. From there, 33 different structural traits are measured to look at how sow structure changes over time, how structural traits are associated with production traits like sow longevity, the effects of nutrition and management on structure, and lastly, looking at genetic aspects of structure and how to better select for it, she said at the 2019 National Swine Improvement Federation meeting in Indianapolis.
“One of the biggest changes we saw were changes in knee angle, and both front and rear pastern angle,” Trenhaile-Grannemann said. “These angles get more flex over time, so we’d select gilts sometime before breeding, but what their knee and pastern angles are at that point, may not be the same as what they are down the road when they are sows a few parities in.”
The takeaway from that is you may not want to select a gilt that has a very straight knee or pastern, but those joints do get more flex as the animal grows.
“A somewhat straight knee or pastern might be ok, while a gilt that has a lot of curvature of their knee and weak pasterns might be more problematic then we may have previously thought,” she says.