By Colton Tripp, K-State Extension news service
A scoop of soybean meal may look much like the next, but Kansas State University researchers are finding that what is inside the feed ingredient – and how it is measured – can vary.
Soybean meal is the primary protein source used in swine diets, making an accurate understanding of its nutrient composition important when developing diets for pigs. However, much of the analytical information available to nutritionists is either outdated, based on smaller surveys or does not include some key measurements used to evaluate soybean meal quality.
Researchers in K-State’s Department of Animal Sciences and Industry set out to develop a more current picture of U.S. soybean meal by evaluating its quality and consistency and determining best analytical practices for measuring the ingredient.
The project included 271 soybean meal samples from 29 processing plants representing 16 companies. The plants accounted for approximately 40% of U.S. soybean meal production, while the companies represented 90% of total production. Samples were collected at two points during the same crop year to help researchers evaluate differences over time.
Researchers analyzed numerous characteristics, including protein, amino acids, fiber, minerals, particle size and indicators used to evaluate protein quality.
Results showed that soybean meal composition was relatively consistent between seasonal sampling periods. However, the processing method used had a greater influence on composition.
Solvent-extracted soybean meal averaged approximately 47% crude protein compared with 42% for extruded-expelled meal, providing a higher concentration of protein that can help support muscle development and growth in pigs. Solvent-extracted meal also contained less ether extract and fewer trypsin inhibitor units.
Researchers also found variation between and within individual processing plants for several characteristics, including ether extract, calcium, trypsin inhibitor units and particle size. Crude protein, amino acids and fatty acids tended to be more consistent.
Those differences matter because nutritionists rely on nutrient values when determining how ingredients fit into swine diets to amplify and aid in growth. The researchers said the new data can provide an updated benchmark for precision diet formulation and soybean meal quality assessment.
“One of the most interesting things we learned was that soybean meal can be relatively consistent for some of the nutrients used in diet formulation, while other characteristics can vary considerably between plants or even within the same plant. For swine producers, understanding where that variation occurs and which measurements are most useful can help them better evaluate their soybean meal and make more informed decisions when formulating diets,” said Sierra Collier, graduate research assistant.
But researchers also found that knowing what is in soybean meal is only part of the equation. How a sample is analyzed can affect the numbers producers and nutritionists receive.
Other Factors That Affect Quality
A second portion of the research compared identical soybean meal samples between four laboratories. Although standardized analytical procedures exist, differences in equipment, calibration, sample preparation and analytical techniques can contribute to variation in results.
Dry matter and crude protein were among the most consistent measurements between laboratories. Ether extract, neutral detergent fiber, and individual amino acids showed greater variation. These findings could help producers better formulate diets to support pig growth and improve feed efficiency.
Trypsin inhibitor measurements also varied, partly because laboratories used different analytical methods. Improving measurement consistency could help producers better evaluate soybean meal quality and support proper protein digestion in pigs.
The findings highlight an important consideration for producers and nutritionists: A laboratory report provides valuable information, but understanding the method behind the number can be just as important.
For swine producers, those differences can ultimately influence decisions made when evaluating ingredients and formulating diets.
“Although we identified important findings related to both soybean meal composition and analytical variation, the most important takeaway was the value of stronger communication between soybean processors and nutritionists,” said Katelyn Gaffield, assistant professor in swine nutrition. “These groups can have competing priorities, but by better understanding each other’s processes, we can identify practical solutions that improve quality for livestock diets while maintaining efficiency in the processing plant.”
Producers, nutritionists, students and others in the swine industry have an opportunity to learn more about soybean meal quality and other K-State swine research at the 2026 K-State Swine Day in Manhattan on Thursday, Nov. 19.
The annual event provides an opportunity to hear about research conducted by K-State swine specialists and how those findings can be applied within the industry. The soybean meal project is one example of research aimed at giving nutritionists and producers more current information to guide decisions.
As soybean meal processing technology continues to change, K-State researchers say having an updated understanding of soybean meal composition will become increasingly important.
The current research provides a benchmark that can support precision diet formulation, quality assessment and communication between soybean processors and animal nutritionists.
Registration and more information about K-State Swine Day can be found online from K-State’s Department of Animal Sciences and Industry.
