Lightweight Pigs, Big Opportunity

Young Animal : Nutrition

Dan McManus, DVM

Young Animal Swine, Technical Sales Specialist

Lightweight pigs are not a new phenomenon in pork production.

For as long as pigs have been raised, the “runts of the litter” have been familiar occurrences.

Looking toward the future, this trend is not likely to change. Lightweights will continue to be an industry reality with increased sow productivity. As litter sizes grow, we will begin seeing even more small pigs. Research shows that for every extra pig in a litter, birthweight decreases by 0.10 pounds.1

Fortunately, there are steps we can take to help small littermates catch up and be productive in their own right. With strategic care and nutrition, these small pigs can represent a big opportunity. 

The lightweight disadvantage
When raised under standard production methods, lightweight pigs start out behind their littermates, and often stay behind – at weaning, end of nursery and, eventually, at finishing. 

The team at the Purina Animal Nutrition Center has monitored more than 10,000 pigs from 2012 to 2015 to determine the impact of starting weight on long-term performance. As shown in Figure 1, a 1-pound lower birthweight resulted in nearly a 6-pound disadvantage at weaning. The lighter pigs at weaning then failed to catch up to the group through the nursery phase, falling behind by nearly 20 pounds at end of nursery (EON), as shown in Figure 2.  

Table of data showing effect of pig birthweight on weaning weightTable of data showing pig birthweight on end of nursery weight

This trend then continues through to finishing. Additional research indicates that low weaning weight ultimately translates into more lifetime days on feed. 

Figure 3 shows data from 1,374 pigs, comparing long-term performance of pigs based on weaning weight. When compared to heavy-weaned pigs, the smallest pigs had significantly lower average daily gain (ADG). The lightest pigs also required 17 more days on feed to finish, and close-out weights were approximately 8 pounds per head less than the heaviest-weaned pigs in the group.

Table showing effect of weaning weights on wean to finish performance in pigs

These two data sets confirm the reality that pigs that fall behind are more apt to stay behind the rest of the group unless they are managed differently. 

Giving small pigs the edge
More than 20 years ago, I learned an important lesson about raising lightweight pigs from a very successful pork producer. His lightweight pigs were leaving the nursery about 10 pounds heavier than those from other farms. When I asked how he made that happen, he simply said, “We feed them differently. They’re different pigs.”

His management strategy – the basic components of which I now recommend – was to implement a “small pig feed budget.” The principles of this approach are: 

  1. Separate the smallest 10 to 20 percent of pigs into designated “small pig” pens at weaning. To account for small pigs being moved, consider initially overstocking the pens by 10 to 20 percent, with the lightest pigs in the pens pulled to the designated small pig pens. If fence line feeders are used make sure the small pens share the same feeder.
  1. Help pigs stay hydrated by providing electrolyte and gel products. These products can support hydration, digestive development, and transitioning to dry feed. Mat feed gel 2 days pre-weaning and for at least 5 days post-weaning. Run electrolytes through a water medicator for 5 to 7 days post-weaning or during times of stress.
  1. At the time of separation into lightweight pens, estimate weight (or use actual weights); count pigs; and place a feed budget card on the feeder. Using the correct weights will help you feed to the individual pig’s nutritional needs rather than to a group average.
  1. Choose a highly palatable pre-starter feed and begin offering it 3 to 5 days pre-weaning to imprint feeding behavior. Offer the same feed through weaning to ease the transition. The initial pre-starter feed should be highly digestible and developed for very young pigs, with enhancements like probiotics and nutraceuticals to stimulate digestive development and strengthen immunity.
  1. Using bags or a pre-starter bin, dispense no more than a day’s allowance of pre-starter at a time, and clean out refusals each day. Fresh feed is especially important at weaning when pigs are first being introduced to a solid feed diet.
  1. Continue to follow a small pig budget for as long as practical, but keep in mind that diet switches for lightweight pigs should be delayed at least one week compared to the rest of the facility.

One farm’s experience
These principles were put to work recently by a producer I work with who made the strategic decision to feed only lightweight pigs. Seeing the potential when managed correctly, he purchased lightweights from large, neighboring sow facilities. 

The average weight of the weaned pigs? Just 8.2 pounds apiece. Data would show us that these pigs had quite an uphill battle. 

We sat down to create a feeding and management program to help these pigs thrive through nursery and on to finishing. With the help of a highly-attentive nursery staff and the six steps listed above, the pigs averaged an end of nursery weight of 52 pounds approximately 51 days later. Even better, mortality rate averaged 2.2 percent; ADG was 0.85 pounds per day; and feed efficiency was 1.53 pounds of feed per pound of gain. 

Experiences like this show that lightweight pigs can reach their potential with specialized transition care and feeding. Separating them into their own production group, rather than allowing them to linger behind the group average, and then managing them similarly to our other pigs can help small pigs represent a big opportunity. 

1Willis, Gawain. “Sow nutrition, health and management.” Purina Animal Nutrition LLC.  Swine VIP Presentation, Sept. 4, 2013. Gray Summit, Mo.