The U.S. sow herd experiences a greater than 50% replacement rate annually, an average parity at culling of 3.5 to 3.8 and fewer than 40 pigs produced during a sow’s lifetime, according to Ken Stalder, an Iowa State University animal science professor, who has reviewed available databases.
The five most common reasons sows leave the herd are:
1) Reproductive failure
2) Feet and leg soundness
5) Postweaning issues
While reproductive failure tops the list of reasons that sows are culled, recent Checkoff-funded research by Stalder suggests that 86% of females are culled for this reason, although their reproductive tracts appeared normal at harvest. Taken together, this indicates that when sows are being culled for reproductive failure, there is actually an underlying factor.
Feet and leg soundness is the second-most identifiable reason why sows leave the breeding herd, says Stalder, adding that the scope of the problems related to soundness issues is probably underestimated.
“When producers cull sows, they check the box for the problem that they last observed,” Stalder says. “So, for example, producers check the box ‘did not conceive.’ If the sow was lame or had feet and legs soundness issues, she may not have had sufficient feed intake during lactation.” He adds, “Thus. the real reason the female did not return to estrus in a timely manner or did not conceive is that she got too thin resulting from a lack of feed intake caused by structural problems or lameness.”
Pork producers need to make sure that they are properly identifying the real cause of problems rather than the latest symptom of a much broader problem. The Pork Checkoff offers educational materials, such as a heat detection poster and a feet and leg soundness poster, to help employees improve their livestock management skills, which in turn will help improve sow lifetime productivity.
For more information, contact Chris Hostetler, director of Animal Science at the National Pork Board at [email protected]  or at (515) 223-2606.