It is well known that a sow needs adequate amounts of feed during lactation in order to maximize its productivity. Fall short on feed intake during the lactation period and sows lose too much body weight, which jeopardizes future reproductive performance. A drop in milk production also results, which jeopardizes the current litter’s growth potential and even survivability. Add them up, and the sow’s longevity in the herd is at risk.

University of Minnesota researchers looked at lactation feeding and its relationship to longevity in high-producing sows in a 1,275-sow herd. Researchers reviewed the association of farrowing and lactation factors that occur and their likelihood to influence which sow would leave the herd before the next farrowing.

“Overall, the risk of sow removal declined as feed intake during the first two weeks of lactation increased,” notes Mark Whitney, University of Minnesota Extension swine specialist. The removal rate declined by 11 percent for each 1-pound increase in a sow’s average daily feed intake. Sows that ate less than 9 pounds of feed a day during the first two weeks of lactation were 27 percent more likely to exit the herd.

Other factors, including litter size (pigs born alive) and the sow’s parity also influenced its chances for removal. “Every additional piglet born alive decreased odds of a sow’s removal by 7 percent,” Whitney notes. Looking specifically at sows’ parity rankings, researchers grouped sows into parity-1 and parity-2, as well as parity-3 through parity-5. They found that those sows were 47 percent and 44 percent less likely, respectively, to be removed from the herd compared to sows of parity-6 or higher.

Other factors, such as the number of mummies or stillbirths that a sow had, whether farrowing was induced, if farrowing assistance was required or there were disease issues, did not appear to influence sow longevity in this study, Whitney says.

“These results show very clearly the importance of ensuring that a sow gets adequate feed intake from the start of lactation, and it’s impact on sow longevity,” he adds.

But what strategies can you use to enhance sow feed intake?

First and foremost, it is crucial that sows are in proper condition before they enter the farrowing unit. “Numerous research studies have shown the strong correlation between overly conditioned sows at farrowing and reduced lactation feed intake,” Whitney notes. “These sows can have a more difficult time farrowing. They recuperate much slower, and they are more likely to lie on or crush piglets compared to sows in proper body condition.”

If sows are too thin entering the farrowing unit, milk production will likely be reduced and the sow’s subsequent reproductive performance, including wean-to-estrus interval and farrowing rate, will be negatively affected.

Therefore, focus on initiating gestation feeding strategies that ensure your sows enter the farrowing unit in tip-top body condition. This means evaluating sow body weight and condition (or backfat) during early gestation and adjusting feed (energy) intake accordingly, Whitney says.

“Too often, producers may increase or decrease their sows’ daily feed allotments during early gestation based solely on the perceived amount of fat the sow is carrying,” he adds. “However, two-thirds to three-fourths of total energy needs are required for maintenance, which is directly related to sow body weight, not condition.”

True to its maternal nature, a sow’s body will designate energy to meet maintenance needs before diverting it to reproductive or growth purposes. Therefore, not taking sow body weight into account can seriously affect reproductive performance.

“It also is important to adjust feed intake allowances based on sow body condition, but only after you’ve taken the sow’s body weight into account,” Whitney says.

Several resources are available to help you determine the right body condition (and weight) for your sows. Check with your area Extension swine specialist, swine nutritionist, veterinarian or your genetic supplier. KansasStateUniversity’s Swine Nutrition department also has a way to make this task a bit easier. Scientists there have developed a cloth tape that helps you take a flank-to-flank measurement, which provides corresponding weight estimates. After that exercise, you can take the information to the ASI Web site at to fine tune the sow’s dietary needs. The tape costs $5 and is available by calling (785) 532-1267, or e-mailing

By providing appropriate gestation and lactation diets, along with managing sow feed intake during both phases, you not only can maximize sow performance, you also help ensure that she’ll be around longer to perform at that level.