Don't base when to cull sows on current performance alone. Consider the bigger picture of lifetime herd performance, and how culling will impact overall herd productivity.
That's according to Don Levis, reproductive specialist and director of the Ohio Pork Industry Center at Ohio State University, Columbus, OH.
More farms are beginning to recognize that if sows are consistently producing 12-14 pigs/litter, that you don't just cull them because they have reached their fifth or sixth parity, he observes.
Rather, it's the sows that periodically show a dip in performance that should be shipped once they reach those higher parities, he says.
Because deciding when sows are past their prime can be a tough choice, Levis suggests using this rule of thumb. “If sows aren't performing as well as they did when they were gilts, or as well as your gilt average is doing, then I say if we are going to continue to make genetic progress, we need to cull them.”
Take care to properly feed sows, especially in the farrowing house. Too often, sows get culled because they are getting out of condition, when in fact workers haven't done a good job feeding them. “We blame it on the sow when it wasn't the sow's fault,” he relates.
Cull sows with a history of lameness or poor condition. Some may become downers and be very hard to remove from the barn.
Culling for poor mothering ability may not be as straight-forward as it sounds, warns Levis. Top-milking sows are used as “nurse” sows. That means they nurse two litters of pigs.
“We find that some of those ‘nurse’ sows later have poor reproductive performance, so they get culled,” states Levis. “They got culled because of what they've done, when in fact, they might be the farm's best sows.” Factor that into the culling program, he says.
Producers say they don't use many “nurse” sows. Levis recalls one large producer he consults for recently figured he used four to five “nurse” sows a week. By the time all the farrowings were added up, it came to 3,000 “nurse” sows in the herd, he points out.
A healthy sow destined for culling can be bred and allowed to farrow if there is an empty crate. “She might give us 6-8 pigs, but that's better than having nothing in the stall,” he says.
Give sows in their prime a second chance if they have one poor litter.
To avoid management errors forcing unjustified culling, periodically walk through sow buildings. Bring in an outside consultant to check sow management practices.