Feeding Soybean Meal Improves Summer Pig Health and Growth
Each summer, pig farmers face the same issue: heat stress reduces feed intake and cuts carcass weight. On average, pigs lose 6 to 12 pounds each during hot months. Across the U.S., this leads to industry-wide losses of around $450 million every year.
Pigs eat less in hot weather to stay cool. But many standard feed ingredients—like corn DDGS, wheat middlings, and corn germ meal—reduce intake even more. These byproducts limit growth just as pigs should be reaching their top market weight during July and August, which is peak pricing season in the U.S.
Adding fat to the diet used to help, but high fat prices make that option too costly. Now, farmers and nutritionists are exploring better solutions that fit their budget.
Recent field research points to soybean meal (SBM) as a practical answer. Known for its protein, SBM also offers health benefits beyond nutrition. It contains special compounds that support pig immunity, gut health, and overall growth—especially during stressful summer periods. Unlike byproducts, SBM does not reduce feed intake.
Dr. David Rosero from Iowa State University supports this strategy. “You need to find the optimal level of soybean meal to support growth performance,” he says. “Our trials showed pigs on high-SBM diets, with no added fat or DDGS, performed best during summer.”
Switching to SBM-rich diets helped pigs gain 5.5 more pounds on average, even in heat. Feed costs were lower, health was better, and farmers earned up to $14 more per pig.
Experts recommend starting this feeding plan in the spring, before summer heat begins. That gives pigs time to adjust to a stronger diet.
This research is part of the Soy Effect series funded by the United Soybean Board.