Modern sows are younger and leaner at mating and have poorer appetites than in the past. Therefore, feeding strategies should aim to minimize body weight loss and maintain a sow’s body condition to ensure longevity in the breeding herd. These strategies can be accomplished by:

  • Establishing feeding programs for gilt development.
  • Controlling feed intake during gestation.
  • Optimizing feed intake during lactation.
  • Optimizing feed intake during the wean-toestrus

A sow’s success in the breeding herd depends on those strategies, with the sow’s lactation nutrient needs as perhaps the most significant. The objective for a lactating sow is to produce a high number of healthy piglets during her reproductive life at a minimal cost. Therefore, a lactation feeding strategy needs to:

  • Optimize milk production.
  • Prevent reproductive failure.

A lactating sow’s energy requirement is dependent on litter size, piglet growth and the sow’s parity. When a lactating sow’s food intake is too low to meet its maintenance and milk production requirements, it mobilizes body reserves. The larger the litter size, the higher the litter weight gain, and the greater the sow’s parity, the higher the feed requirement. However, because of restricted feed intake capacity, many lactating sows do not meet their nutritional requirements — or those of the piglets — which means the sow mobilizes body tissues. Excessive sow body weight loss results in a prolonged wean-to-estrus interval and decreased subsequent litter size.

Low feed, low energy and low protein levels during lactation cause a prolonged wean-tore-
mating interval, especially in first-litter sows. Those sows with a weight loss of more than 7.5 percent and more than 12.5 percent during lactation showed a prolonged wean-toestrus interval. (See table 1.) In second-parity sows, the effect was less pronounced. For sows at parity three or more, weight loss in lactation had even less influence.

A delay in estrus after weaning may result in poor reproductive performance. Research shows that sows inseminated five days after weaning had more piglets born alive and a higher farrowing rate after the first insemination than sows inseminated between days nine and 12 post-weaning.

But when a sow mobilizes body tissues during lactation, the smaller subsequent litter size is due to effects on embryonic survival versus ovulation rate. (See table 2.)

So, here are some ideas to stimulate lactation eed intake.

  • It is well established that increasing feed intake during pregnancy reduces voluntary feed intake during lactation. Depending on the gilt’s or sow’s body condition at breeding, feed 3.5 pounds to 4.5 pounds of feed (13.5 MJ ME/kg) 30 days after breeding and increase that by 1 pound every 30 days thereafter. So, a bred sow or gilt consuming 3.5 pounds of feed 30 days after breeding will be eating 5.5 pounds before entering the farrowing room.
  • When the farrowing room temperature exceeds 60.8° F, feed intake declines. Voluntary feed intake decreases by 0.28 pound for every 1° F increase in ambient temperature. If the farrowing room temperature is 70° F, a lactating sow’s voluntary feed intake drops by about 2.8 pounds a day.
  • Water flow rate should be 35 seconds per pint and a lactating sow should consume 2.5 gallons to 7 gallons per day.
  • Ensure rapid increase in feed after farrowing with no drop in feed during lactation.

Remember, a lactating sow’s nutrient requirement is very high, and if it falls short, the sow will use body reserves to accommodate maintenance and milk production. Excessive loss of body reserves will hurt the wean-to-estrus interval and subsequent litter size. Adopt feeding strategies to minimize
body tissue loss and to ensure your sows’ longevity.

Weight Loss Impacts Return to Estrus

Here's a look at the effect of body weight loss during lactation (as a percentage of body weight after farrowing on the wean-to-estrus interval).

Feeding Rate Influences Embryonic Survival

Low feeding levels during lactation may have negative effects on embryonic survival and this may influence subsequent litter size.