There is a benchmark figure on PigCHAMP's performance monitor that Minnesota veterinarian Tom Wetzell believes is overlooked when appraising sow longevity — pigs weaned/lifetime female (PW/LF).
Pigs weaned/lifetime female measures the total number of pigs a sow weans before she leaves the breeding herd. “It's a good marker for sow productivity that we haven't looked at,” says Wetzell, South Central Veterinary Associates, Wells, MN.
One of his clients, Steamboat Pork, may be setting the gold standard on that production figure. The 1,200-sow cooperative near Klossner, MN, weaned 52 pigs/lifetime female in 2004 (Table 1). The average reported in the 2003 U.S. PigCHAMP summary was 32.75.
That means every female entered into Steamboat's herd is producing 20 more pigs in her lifetime, on average, than sows in the U.S. database. “And that is longevity,” adds Wetzell. “There are individuals here that have produced over 100 pigs before they leave the herd.”
Average parity of farrowed sows is 4.1, with some remaining in the herd as long as their 10th parity. Close to 20% of the herd consists of Parity 6 or older sows. More importantly, only 13% of sows are culled before the third parity.
Unit manager Kevin Portner doesn't have a secret recipe for keeping sows around, just good, old-fashioned animal husbandry on a daily basis. “Our philosophy is to keep it as simple as possible,” he says.
Portner's main focus is production. The F1 Yorkshire-Landrace sows are never culled because of poor condition, nor does Portner cull on farrowing performance in the first two parities.
The Removal Analysis Report from PigCHAMP provides a breakdown of reasons animals leave the herd (See Figure 2). “It's an important report to monitor,” says Wetzell. “High-attrition herds have a lot to do with young females being culled prematurely. We need to find ways to get those to the second parity and beyond.”
University of Minnesota veterinarian John Deen, probably the leading expert on sow attrition in the United States, has studied retention problems and found that herds that didn't remove more than 14% of their gilts by their third parity had the best performance. Steamboat's figure was 13% for 2004.
Average born alive is 10.8 pigs at Steamboat Pork, with 9.8 weaned. Average age at weaning is 19 days, and weaning weight averages 14 lb. Pigs weaned/mated female (PW/MF) was 23.5 last year. The 2003 PigCHAMP summary reported an average PW/MF of 20.1 pigs.
Portner would like to see Steamboat Pork's PW/MF average go up 1.5 pigs, but says pig size is also important. “The quality of pig is something many sow farms forget about,” he points out. “Our birth weight is higher and pigs are a good size at weaning.” Adjusted 21-day litter weight averages 150 lb.
Sows are individually micro-managed in gestation crates. Great care is taken not to over or under feed. Thin or heavy sows are grouped in gestation stall rows according to visual appraisal. Overhead hoppers are adjusted to deliver more or less ration (Table 2 shows averages).
Backfat has been monitored in the past to determine if gilts were carrying too little or too much fat. Real-time ultrasound found gilts with too little backfat, which was remedied by supplementing fat in the ration and slowing rate of gain.
Shareholder Dean Compart, who also supplies the co-op's genetics, prefers real-time backfat measurement. The Nicollet, MN, seedstock producer has used a less expensive, hand-held, A-mode machine, but feels it underestimates backfat in pigs that are slightly fatter.
“Pigs that are in the 0.7- to 0.8-in. fat area could have a third fat layer separated by a membrane that the A-mode probe doesn't penetrate,” Compart explains. “It returns a reading of 0.6 in. of fat in pigs that with real-time are 1.2 in. at the same location. The A-mode meter will work on truly lean pigs, probably gilts less than 0.6 in. fat measured at the last rib.”
Feed intake is closely monitored in lactation with help from Kansas State's Lactation Calculator (Table 3). Monitoring monthly and seasonal fluctuations allows the production team to make adjustments in nutrient densities and identify potential problems before they affect performance on a long-term basis. Finicky gilts will get the more familiar gestation feed if they're not eating in the farrowing house. Sows are allowed brief periods of exercise when not eating in farrowing, and great pains are taken to keep the feeder hoppers clean.
Older-parity sows usually leave the herd when milking ability starts to suffer. Notes are entered on individual sow cards as to the status of milking ability as an aid in making culling decisions, mostly based on visual appraisal of the litter. Her days are numbered if there's a CIP (cull if possible) written on the back of the card. “But old girls that still produce, stick around as long as there's an open crate,” Portner points out.
Biosecurity may not be directly related to sow longevity, but this farm is as good as it gets, according to Wetzell. Dead pigs are disposed of off site. A separate entry accepts deliveries. Trailers are washed and disinfected at a separate site. There are four shower rooms for employees and the rare visitor. But the main health control measure was closing the herd. “That plays into our story on attrition,” he says.
More than two years ago, PRRS entered the herd — the new virus was traced to contaminated gilts from off-site isolation units. It wasn't long until they built their own isolation rooms connected by a long hallway to the rest of the facility. Replacement gilts are farrowed in the commercial herd and moved to the isolation nursery at weaning. Nine weeks later, they move to one of the three grower rooms in the company of crated boars.
Gilts stay in isolation until ready to breed — at 300 lb. or 230-240 days. Most are bred on second or third heat.
The constant boar exposure in isolation has been very helpful in coaxing gilts to cycle, says Portner. “Getting that sexual maturity at the right age also helps with longevity,” points out Wetzell.
There is no acclimation stage, which also may help to lower the gilt attrition rate.
A big challenge to the industry right now is how to transition naïve gilts into farms with health issues, notes Com-part. “Those animals get sick and run down, and end up leaving the herd early. Steamboat is raising them on the farm, which pays a bonus in the future.”
Compart's Boar Store provides the semen for the operation, 90% of which are York-Landrace cross to maximize heterosis for maternal characteristics. A pureline Yorkshire population maintains an elite nucleus female line, long selected for high total born and superior milking ability.
Body type is also credited with the low number of sows Portner culls for non-productive reasons. Compart says they have always emphasized width and length of body and good feet and legs. Pasterns are slightly sloping so there's more cushion to stand, he points out.
Those culled sows are what Portner calls “good, top-grade” animals that bring top dollar. “We are forced to cull our animals because of replacements coming in,” he says. “We really work hard at this. Heavy sows are worth the most money, which adds value to the operation.” Average cull price was $229/sow in 2004. Mortality rate in the sow herd is 4.7%.
Wetzell looks at sow attrition as a welfare issue, and describes Steamboat as welfare friendly. “They have the best interest of the individual female in mind. It's all observation,” he maintains. “Quality care is a lost art. Is she drinking water? Is her breathing normal? Do her skin and stools look okay? Much of our industry has totally lost track of sow stockmanship.”