Attrition is never a good thing — after all, it’s about loss. The key is to work to minimize its impact on your business.

John Deen, DVM, at the University of Minnesota, conducted a research project looking into sow attrition rates and found an interesting conclusion.

Deen contends that in terms of attrition in the sow herd, the major focus should be on the average parity of sows removed from the herd. His answer to that is to decrease the number of young sows and gilts that are removed.

Here are some risk factors associated with sow removal.

  • Farrowings: As litters per sow increase, so does the replacement rate, though average parity removed remains stable.
  • Farrowing rate: Reproductive failure is the largest reason for removal, with the two-strikes-and-you’re-out rule almost guaranteeing a low average parity removed.
  • Herd size: Mortality rates increase with herd size.
  • Stillbirths: Sows with more stillbirths are more likely to die or be culled subsequent to stillbirths.
  • Stockman training and time: People and management play an important role in increasing sow longevity today.
  • Gilt flow: The largest attrition factor when viewed on a week-by-week basis is the availability of gilts. Many herds face a feast or famine supply of available gilts.

The underlying premise of parity segregation is that a developing gilt is a unique animal and by treating her as a sow we shortchange her physical development and her potential as a productive member of the sow herd.

To address the unique growth, development and health status, Camille Moore, a Quebec-based veterinarian, recommends the following practices to improve gilt growth, development and longevity.

Special gilt handling procedures include:

  • Move gilts as all-in/all-out groups of 20 pigs at 55 pounds and allow 10 square feet of space in the gilt barn.
  • Health challenges need to occur before 130 days of age for optimum acclimatization. Seeder pigs are brought in to help expose gilts to pathogens that they will encounter.
  • Proper immunity can take 100 days to develop.
  • To maximize protein deposition, feed a diet higher in protein then a regular finishing diet up to 135 days of age.
  • After 135 days, the diet should focus on backfat deposition. This means 7 percent to 10 percent more energy and 5 percent less protein (about 13 percent total) than the lean-muscle diet, says Moore.
  • Provide 16 hours of light per day once the gilt has reached 150 days of age.
  • At 185 days of age, or 275 pounds, gilts are moved to a gilt-breeding barn equipped with self feeders and placed in pens of 10. They receive either fence-line exposure to a boar or in-pen exposure to vasectomized boars.
  • Gilts are then exposed to boars three days prior to the next expected heat, bred 12 hours after estrus and every 12 hours until heat ends.

“The key factor for insuring long-term retention of gilts in the breeding herd is to know each gilt’s weight, age and backfat at first mating,” stresses Moore.

To “feed gilts correctly” figure on an extra $6.50 to $8.20 per gilt. “People question the cost of feeding the levels of protein and energy that improve longevity,” says Moore, “but they need to remember this is a capital investment in animals that represents 20 percent of their herd.”

During lactation, Parity-1 gilts often lose body condition quickly, necessitating a nutrient-dense diet fed up to three times per day. “In reality, general body condition at first weaning is probably the most important factor for retention in the sow herd,” he adds. 

In the 12,000-sow Canadian operation practicing parity segregation, Moore reports these results:

  • 11.5 pigs born alive per gilt.
  • 10.1 pigs weaned per gilt at 17.7 days.
  • Female culling rate at first parity, 18 percent.
  • Average sow parity for the entire system is 4.4, with a replacement rate of 48 percent, including a mortality rate of 7.5 percent.

While these numbers represent a significant improvement in this herd, Moore stresses there is still a lot to be learned about the animal- and disease-management issues related to parity segregation.

“We are in the infancy stage of understanding all the pros and cons of parity segregation,” he admits. 

By Natalie Knudsen, freelance writer from Mankato, Minn.