Pork producers know the costly toll of summer heat stress: as barn temperatures climb, pigs consume less feed, growth stalls and carcass weights dip. This costs the U.S. swine industry hundreds of millions of dollars each year. But according to commercial nutrition research, the window to prevent next summer’s weight drop is open right now.
“The pigs we’ll market next summer go into the barn this winter, and that’s when feeding programs are established,” “If you wait until the heat shows up to rethink carcass weights, the formulation decisions that matter have already passed.”
“The pigs we’ll sell next summer go into the barn this winter, and that’s when the diets get set,” says Tim Bardole, an Iowa farmer from Rippey who raises both pigs and soybeans. “If you wait until the heat shows up to think about carcass weights, the formulation decisions that matter have already been made.”
Commercial Trials Show Measurable Gains
As part of the United Soybean Board’s (USB) Soy Effect research series, nutritionists at a large commercial pork system evaluated diets featuring higher inclusion rates of soybean meal for pigs headed to summer markets. Rather than relying solely on traditional high-energy rations, the higher-SBM formulations provided denser amino acid profiles to compensate for reduced summer feed intake.
The results were clear: pigs on the higher-SBM program achieved an average 5.5-lb. heavier carcass weight over the summer while simultaneously reducing net feed costs per pig. A subsequent 2024 commercial trial in Iowa reinforced the findings, demonstrating favorable average daily gain and feed conversion even during a milder summer.
In a 2026 Soy Checkoff survey of swine nutritionists who together represent about 3.6 million sows, 60% of respondents said they had increased soybean meal in late-finishing diets to help offset the summer dip.
“The success of the pork and soybean sectors is deeply interconnected,” says USB CEO Courtney Knupp. “When research proves that nutrient-dense soybean meal can safeguard swine performance through summer heat stress, it delivers real economic value to livestock producers while strengthening demand for U.S. soy.”
Modeling Margins with Feed4Profit
Because the economic advantage of adjusting rations depends on shifting commodity prices, USB partnered with Iowa State University to launch Feed4Profit (feed4profit.net). The free, publicly accessible digital model allows swine producers and nutritionists to input local ingredient costs, model pig performance responses, and compare projected income over feed costs across a 12-month horizon.
With winter rations currently being locked in, producers can use the tool to determine whether boosting soybean meal will capture the summer market premiums that heavier carcass weights command. Learn more at feed4profit.net.
