Solving the pig mortality puzzle takes a team, researchers say

High mortality rates have plagued pig farmers for years. In the last decade, sow mortality rates have increased, costing farmers about $800 to $1,000 per loss.

"As an industry, we know that we are not where we want mortality to be today, so we need to keep working at it," says Mike Tokach, a professor and researcher at Kansas State University. "In terms of mortality, you could blame it on the geneticists or the veterinarian, but it is going to take getting everybody involved." 

Last year, the Pig Livability Project, a five-year program funded by the National Pork Checkoff and the Foundation for Food and Agriculture Research, began research to find solutions to increase sow longevity and piglet livability through better management practices. 

The Pig Livability team recently found several revelations in its studies of raising gilts, caring for sows, and weaning piglets.

Root causes putting a dent in sow herds  

In many gestating barns, the loss of sows is rooted in prolapse, the weakening of internal tissues supporting the pelvis, rectum, vagina, and uterus. Jason Ross, an Iowa State University (ISU) professor, says that researchers attributed 20% to 30% of mortality on farms to sow prolapse.

"It's a costly problem for the industry that wasn't one 10 or 12 years ago," he says.

How does prolapse happen? Researchers are still getting to the root cause of prolapse, Ross says.

One study proved that thin sows or sows bred at a lighter weight were at a higher risk than normal-weight or overweight sows. Ross says farmers can use the industry's body conditioning score as a guide for bumping up feed intake for thinner and late-gestation sows to lower their chances of pelvic organ prolapse.

For some farms, mortality begins before conception happens in gilts. The current industry’s approach to gilt care — with vaccines and feeding extra calcium and phosphorus as a young female’s farrowing date gets closer — could be exhausting that gilt’s immune system, which can affect her whole body, even her feet, says Laura Greiner, a professor at ISU.

Greiner estimates that, on average, farmers will give 11 vaccinations to a gilt from 50 pounds to when she is bred. Most are right before conception, which can cause the immune system to have a high inflammatory response across the gilt's body.

"That immune system is just going crazy," she adds. 

A highly active but naïve immune system could cause long-term lameness, leading to mortality. It’s also a culling driver in sow herds.

Greiner and her team focused on approaches to remedy joint health through the diet.

"We know as an animal grows, if they grow very fast, they develop lesions within their joints, and those lesions over time become arthritic," she says.

A common practice on pig farms, especially when feed prices are more affordable, is for farmers to add some fat such as linoleic acid, a nutrient from corn oil, to a gilt’s diet to support reproduction.

Greiner's first study found that when gilts were fed a low-fat or no-fat diet between 50 pounds to puberty, there was less inflammation in their joints from synovial fluid. This study also confirmed that feeding sows or gilts four 1.5-pound meals reduced the need for assistance during farrowing and piglet deaths, says Greiner.

In a second study, Greiner's team fed different ratios of diets between gilts and barrows to mimic the effects it would have on joint and immune systems, but instead, they uncovered an odd result — the gilts grew at the same rate as the barrows.

"That is something we are trying to understand because whatever that fat is doing in that diet or that ratio, it’s changing something biologically," she says. "That's something that makes me nervous. There could be long-term consequences if we're manipulating the gilts to behave like a barrow."

Greiner and a research assistant have an ongoing study at an Iowa farm with about 11,000 gilts on a low-energy diet compared with a normal-energy diet.

"We are trying to slow down gilt growth by about a month and see if that improves the longevity of those females mainly through lameness," she says.

Researchers help farmers reduce sow mortality

Chris Rademacher, a clinical veterinary diagnostic professor at Iowa State University, has been helping some sow operations create a system to identify at-risk sows in the early stage of illness.

Rademacher says the swine farm staff quickly learned the early signs, such as a sow not eating or getting up when employees walked by the pens. A few farms he has worked with created a flagging system requiring one employee in front dropping feed and one person behind that would flag sows for follow-up treatment.

"The breeding and gestation guys got it the right way. They realized if they spend more time treating the sows earlier, that's fewer dead sows," he says.

Using Rademacher's flagging system, one farm reduced mortality by 25% after two weeks.

"It was amazing just how, by identifying those sows early, what a better success rate we had with lower mortality rates," he says.

The weaning struggle

The most challenging hurdle for most piglets can be weaning — moving off the mother sow's milk — and embracing feed as a life source. Weaning is also a struggle for many farmers, says Tokach.

Tokach's research confirmed that creep feeding before weaning is essential to reduce the number of piglets that lose weight after weaning and to improve growth performance.

However, it also found that mat feeding in the nursery after weaning reduces a piglet's mortality. "We learned that both those strategies have an impact. It's not enormous, but it's a 1.5% improvement, which is important," Tokach says.

Rademacher adds that the age of the piglet when it goes through weaning also significantly impacts livability.

"One highlight was weaning age; it was a driver," Rademacher says. "The older the pigs were when they were weaned, the higher their survivability and the lower their mortality."

Tokach's research also looked at the genetic side of piglet mortality. The results were close to his hypothesis: early maturing genetics lost weight the first three days after weaning versus pigs from late-maturing lines.

"This shows that genetics is a crucial piece of the puzzle in getting pigs up on feed," he adds.

When his team added creep feeding, it benefitted the lifetime performance of late-maturing genetic pigs compared with early-maturing genetics.

"The big takeaway for me is we can impact mortality with nutrition, but the impact is relatively minor compared with the results we have seen with health and genetics," Tokach says.