By: Casey L. Bradley, Ph.D. - June 9th, 2026; President and Founder of AnimisticÂ
Trypsin inhibitors in soybean meal deserve close attention because soybean meal has earned its place as one of the most important protein ingredients in animal nutrition. It is widely available, highly digestible when properly processed, and provides an amino acid profile that works well across monogastric species including pigs, poultry, fish, dogs, and cats.
But soybean meal is not a static ingredient.
Its nutritional value is shaped not only by crude protein, amino acid profile, and digestibility coefficients on paper, but also by how the soybean was grown, processed, heated, transported, sampled, and monitored. One of the most important anti-nutritional factors connected to soybean processing is trypsin inhibitor activity.
At World Pork Expo 2026, Animistic sat down with Jeremiah Nemechek of Novus International to discuss why trypsin inhibitors are gaining renewed attention in swine nutrition. The conversation was recorded for The Real P3 Podcast and will also be available on the Animistic YouTube Channel.
While the discussion began with pigs, this topic reaches much farther than pork production. Trypsin inhibitors matter to anyone formulating for monogastric animals because the basic biology is shared: if digestive proteases are inhibited, protein utilization suffers.
For Animistic, this topic is not theoretical. It connects directly to a recent field case in broilers, where reduced growth performance was traced back to a soy issue. The birds were consuming diets that appeared nutritionally sound on paper, but field observations and rapid performance recovery after fresh feed strongly pointed toward undercooked soy and elevated trypsin inhibitor activity as the likely cause.
That is exactly why this conversation matters.
Trypsin inhibitors are naturally occurring proteins in soybeans that interfere with digestive enzymes, especially trypsin and chymotrypsin. These enzymes are essential for breaking dietary protein into smaller peptides and amino acids that the animal can absorb and use for growth, maintenance, immune function, reproduction, and tissue repair.
Soybeans contain two major types of trypsin inhibitors:
Kunitz trypsin inhibitor, which is larger, more heat-labile, and generally easier to reduce through proper thermal processing.
Bowman-Birk inhibitor, which is smaller, more heat-stable, and can be more resistant to heat treatment because of its compact structure and multiple disulfide bonds.
The practical challenge is that heat is both the solution and the risk.
Too little heat, and trypsin inhibitors remain active. Too much heat, and protein quality can be damaged through reduced amino acid availability, especially lysine. This creates a narrow processing window where soybean meal must be heated enough to reduce anti-nutritional activity but not so aggressively that the protein becomes less valuable.
That balance is not always achieved.
Trypsin inhibitors reduce performance through several related mechanisms.
First, they directly inhibit digestive proteases. When trypsin and chymotrypsin are blocked, dietary protein is not digested as efficiently. This means fewer amino acids are available to the animal.
Second, the animal may respond by increasing pancreatic enzyme secretion. The pancreas works harder to produce more digestive enzymes, which can lead to pancreatic enlargement, especially in poultry. This response also increases endogenous amino acid losses because digestive enzymes themselves are proteins.
Third, reduced protein digestion can affect gut health. Undigested protein reaching the lower intestine may alter microbial fermentation patterns and contribute to poorer litter, enteric stress, or greater susceptibility to digestive disorders depending on the species and production environment.
In practical terms, elevated trypsin inhibitor activity can show up as:
This last point is critical. A diet can look correct in the formulation software and still fail biologically if the ingredient quality is not what we think it is.
As Jeremiah explained during the interview, “the amount of variation… is way beyond anything I ever thought.”
That variation is why trypsin inhibitors deserve renewed attention.
Much of the recent conversation around trypsin inhibitors has focused on nursery and growing pigs. This makes sense because young pigs are highly sensitive to protein quality, gut health challenges, and feed ingredient variation.
Recent swine research has shown that increasing dietary trypsin inhibitor concentrations can linearly reduce growth performance and protein digestibility. In nursery pigs, elevated soybean-derived trypsin inhibitor protein has been associated with reduced body weight, average daily gain, average daily feed intake, feed efficiency, nitrogen digestibility, and nitrogen retention.
Jeremiah summarized the concern clearly in the interview: “TRIPS inhibitors are having a bigger impact on performance than I ever imagined.”
That statement captures why the industry is revisiting this topic. Trypsin inhibitors were not unknown. Nutritionists have understood them for decades. But what is changing is our awareness of how much variation may exist in commercial soybean meal and how that variation may influence real-world performance.
A swine diet may be formulated with the same soybean meal inclusion rate week after week, but if the trypsin inhibitor activity changes, the pig may not experience that diet the same way.
That creates a practical problem for nutritionists, feed mills, and producers.
The formula did not change. But the biology did.
For poultry, trypsin inhibitor activity has long been connected with reduced amino acid digestibility, poorer growth, increased pancreas size, and compromised feed efficiency.
Broilers are especially useful indicators because they grow quickly and respond rapidly to changes in feed quality. When soybean meal is underprocessed, broilers may show reduced performance in a short period of time. In some cases, the feed may pass routine nutrient checks but still fail biologically because anti-nutritional factors were not adequately controlled.
That is what made Animistic’s recent field experience so relevant.
In the broiler case, reduced growth occurred in birds consuming feed that should have supported performance. After evaluating the situation, undercooked soy was identified as the likely issue, with trypsin inhibitor activity considered the most probable reason for the reduced growth. Once fresh feed was provided, the birds rebounded.
That rebound matters. It illustrates that the issue was not simply genetics, management, environment, or disease pressure. Feed quality was a key driver.
For broilers, this has several implications:
This is why Animistic approaches field nutrition with both scientific depth and practical pattern recognition. We do not look at one species in isolation. We compare what we know from pigs, poultry, companion animals, and other monogastrics to identify likely biological explanations faster.
Trypsin inhibitors are most commonly discussed in swine and poultry, but the concept applies across monogastric nutrition.
In aquaculture, soybean meal inclusion has been studied extensively as fishmeal replacement continues to expand. Some fish species are more sensitive than others to soybean anti-nutritional factors, including trypsin inhibitors, lectins, oligosaccharides, and antigenic proteins. Salmonids, for example, can be particularly sensitive to soy-related anti-nutritional factors depending on ingredient quality and processing.
In companion animals, extrusion often helps mitigate many anti-nutritional factors, including trypsin inhibitors. However, as pet foods incorporate more plant proteins, pulses, legumes, and specialty protein sources, the same principles apply. Processing quality matters. Protein digestibility matters. Anti-nutritional factors matter.
In young animals, stressed animals, high-performance animals, and animals with digestive sensitivity, the margin for ingredient error becomes smaller.
That is why Animistic often uses a comparative animal nutrition approach.
The term is similar in spirit to comparative animal physiology. Instead of viewing each species as completely separate, comparative animal nutrition recognizes that animals share biological principles while also having species-specific differences. A broiler is not a pig. A pig is not a salmon. A dog is not a laying hen. But all monogastric animals depend on digestive enzymes, amino acid availability, gut integrity, and ingredient quality.
When something disrupts protein digestion in one species, it may help us ask better questions in another.
That cross-species thinking is one of Animistic’s strengths.
One of the most important themes in Jeremiah’s interview was variation.
Historically, many nutritionists may have assumed trypsin inhibitors were present in soybean meal but not at levels high enough to significantly affect performance when the soybean meal was commercially processed. That assumption is being challenged.
Trypsin inhibitor activity can vary because of:
This variation means one soybean meal source may not behave like another. Even soybean meal from the same plant may differ across time.
During the interview, Jeremiah emphasized that the industry needs more information, saying, “The best way to do that is… more sampling, more testing.”
That is a simple statement, but it has major implications.
If we only sample soybean meal occasionally, we may miss the variation that is actually driving animal performance. A quarterly or annual result may not represent the ingredient being fed today. A single wet chemistry value may not capture load-to-load variation. And if the issue is intermittent, it may be missed entirely unless sampling is frequent enough to detect it.
One reason trypsin inhibitors have not always been monitored routinely is that traditional wet chemistry analysis can be expensive, time-consuming, and variable between labs.
That creates a practical barrier.
If an analysis takes too long or costs too much, it is less likely to be used frequently. If results vary between laboratories, nutritionists and feed mills may lose confidence in the number. As a result, the industry may rely on indirect measures such as urease activity, protein solubility, protein dispersibility index, or historical supplier trust.
Those tools can be useful, but they do not always fully explain biological performance.
This is where technologies like near-infrared spectroscopy, or NIR, become interesting. NIR does not replace all analytical chemistry, but it can make frequent screening more practical when equations are properly developed, validated, and interpreted. Jeremiah discussed Novus’s work in developing NIR equations to better evaluate trypsin inhibitor levels and help the industry monitor variation more efficiently.
For feed mills and nutrition teams, the long-term goal is not simply to generate more data. The goal is to generate actionable information.
Can we identify high-risk soybean meal before it affects animals? Can we adjust formulation or enzyme strategies based on ingredient quality? Can we link analytical results to performance outcomes? Can we improve purchasing specifications or supplier conversations?
Those are the questions that matter.
Managing trypsin inhibitors requires an integrated approach.
The first and most obvious solution is proper soybean processing. Thermal processing remains the primary method for reducing trypsin inhibitor activity. However, the processing target must be balanced. Underprocessing leaves anti-nutritional factors active. Overprocessing can damage amino acids and reduce protein quality.
Extrusion, hydrothermal processing, toasting, fermentation, and other technologies can all play roles depending on the ingredient and species.
The second solution is better quality control. This includes more frequent testing, better sampling procedures, more consistent analytical methods, and closer communication between nutritionists, feed mills, ingredient suppliers, and production teams.
The third solution is formulation awareness. Nutritionists should recognize that soybean meal is not just a crude protein source. It is a biologically active ingredient with potential variation in digestibility, anti-nutritional factors, and amino acid availability.
The fourth solution is enzyme technology. Proteases may help offset some of the negative effects of trypsin inhibitors by supporting protein digestion. Research in poultry and swine suggests that protease responses may be more pronounced when trypsin inhibitor activity is higher, which aligns with classic enzyme-substrate logic.
This creates an interesting future opportunity: more dynamic nutrition strategies where soybean meal quality, trypsin inhibitor activity, crude protein, reactive lysine, and protease inclusion are considered together.
The fifth solution is plant breeding and gene editing. Low-trypsin-inhibitor soybean varieties, Kunitz-free lines, and emerging gene-editing technologies may reduce the anti-nutritional burden at the crop level. These innovations could reduce the need for aggressive heat treatment and help preserve protein quality.
However, none of these solutions work in isolation. The future will likely involve better soybean genetics, improved processing, rapid testing, targeted enzyme use, and nutritionists who understand how to apply the data across species.
At Animistic, we work across species, production systems, and product categories. That is not an accident. It is central to how we think.
We are comparative animal nutritionists.
That means we use the shared principles of animal biology while respecting the unique needs of each species, life stage, and production environment. A trypsin inhibitor issue in broilers can inform how we think about nursery pigs. Swine research can help us ask better questions about poultry feed quality. Aquaculture data can remind us that plant proteins bring both opportunity and complexity. Companion animal nutrition can challenge us to think differently about processing, protein quality, and digestibility.
This cross-species lens is especially important as the animal nutrition industry continues to innovate. Companies are developing new feed additives, enzymes, fermented ingredients, specialty proteins, functional ingredients, and processing technologies. These innovations need more than a sales story. They need scientific evaluation, practical testing, and field interpretation.
That is where Animistic is different.
We are not just looking at the diet on paper. We are looking at the animal in front of us, the ingredient behind the diet, the processing behind the ingredient, and the biological response that tells us whether the system is working.
The recent broiler soy issue is a good example. The birds told the story first. Reduced growth signaled that something was wrong. Evaluation of the feed and the response to fresh feed helped identify undercooked soy as the likely cause, with trypsin inhibitor activity as the probable mechanism. That type of field problem requires both technical nutrition knowledge and practical experience across species.
This is why Animistic continues to work with companies to develop, test, and refine innovations that optimize nutrition and animal well-being. Whether we are working with a herd, flock, kennel, colony, or individual animal, our goal is the same: to use science plus heart to help animals and companies thrive.
Trypsin inhibitors are not a new topic, but they are newly relevant.
As soybean meal inclusion shifts with commodity markets, synthetic amino acid pricing, sustainability pressures, and supply chain variation, nutritionists need to pay closer attention to soybean quality. A soybean meal that looks acceptable on paper may not always perform the same in the animal.
For pigs, poultry, fish, and companion animals, protein quality is more than crude protein. It is digestibility, amino acid availability, processing adequacy, anti-nutritional factor control, and biological response.
The key takeaway is simple: variation matters.
And when variation matters, testing matters. Field observation matters. Cross-species experience matters.
That is why this conversation with Jeremiah Nemechek and Novus is so timely. Trypsin inhibitors are not just a soybean processing issue. They are a performance issue, a gut health issue, a formulation issue, and an innovation opportunity.
Listen to the full conversation on The Real P3 Podcast, watch the interview on our YouTube Channel, and learn more about Novus International’s work in animal nutrition at Novus International.
Barth et al., 1993; Clarke & Wiseman, 2005, 2007; Gertler et al., 1970; Heger et al., 2016; Kim et al., 2024; Kuenz et al., 2020; Miller et al., 2025; Nisley et al., 2025; Palliyeguru et al., 2011; Perez-Maldonado et al., 2003; Takács et al., 2022; Wedekind et al., 2020; Xiao et al., 2025.
