Research shows that heating plant-based pig feed made from peas and lentils, combined with adding enzymes after heating, significantly improves how much nutrition pigs can absorb. According to Gram Research analysis, extrusion processing increased gross energy and protein digestibility in both low and high-protein plant-based diets, with enzyme addition after heating providing further improvements. This processing method could help farmers use more affordable plant-based ingredients while maintaining pig nutrition.
According to Gram Research analysis, scientists tested whether heating and adding special enzymes could help pigs digest plant-based foods better. They fed growing pigs diets made from field peas and lentils—affordable alternatives to soybean meal—and compared raw versions to heated versions with or without added enzymes. The results showed that heating the food significantly improved how well pigs could absorb nutrients, and adding enzymes after heating made it even better. This discovery could help farmers feed pigs more sustainably while keeping them healthy and growing properly.
Key Statistics
A 2026 research article found that extrusion processing of pea and lentil-based diets fed to 8 growing pigs significantly increased gross energy and crude protein digestibility compared to raw diets.
In the same 2026 study, adding an enzyme blend (containing cellulase, xylanase, protease, and phytase) after extrusion further improved standardized ileal digestibility of essential amino acids in growing pig diets.
Research on 8 pigs showed that adding enzymes before extrusion actually reduced digestibility improvements, likely due to heat damage to the enzymes during the extrusion process.
The Quick Take
- What they studied: Whether heating (extrusion) and adding enzyme blends to plant-based pig feed made from peas and lentils would help pigs digest and absorb the nutrients better
- Who participated: Eight young pigs (weighing 22-23 kg each) that had special tubes surgically placed in their digestive systems to collect samples. Each pig ate eight different diet versions over eight 9-day periods.
- Key finding: Heating the plant-based feed increased how much protein and energy pigs could absorb by significant amounts. Adding enzymes after heating improved results even more, while adding enzymes before heating actually reduced benefits due to heat damage.
- What it means for you: Farmers could use more affordable plant-based ingredients like peas and lentils in pig feed if they heat and treat them properly, potentially lowering feed costs while maintaining pig health. However, this is early research on a small number of pigs, so larger studies are needed before widespread farm use.
The Research Details
Researchers created two different pig diets: one with regular pea and lentil flour (lower protein) and one with concentrated pea and lentil protein (higher protein). Each diet was prepared four different ways: raw (unprocessed), heated using a machine called an extruder, heated with enzymes added before heating, and heated with enzymes added after heating. The enzyme blend contained four types of enzymes designed to break down different components of plant material.
Eight young pigs with special collection tubes in their intestines ate each of the eight diet versions in a rotating pattern. Each diet was fed for 9 days, with samples collected during the last 4 days of each period. Scientists measured how much of the nutrients the pigs could actually absorb by analyzing their intestinal fluid and feces. They used a special marker (titanium dioxide) to track food movement through the digestive system.
This type of study design, called a Latin square, ensures each pig gets every diet version, which reduces the effects of individual pig differences on the results.
Understanding how to process plant-based ingredients is crucial because peas and lentils contain compounds that block nutrient absorption. By testing different processing methods, researchers could identify the best way to make these affordable ingredients work as well as expensive soybean meal. This matters for sustainable agriculture and reducing feed costs.
The study used a rigorous design where each pig served as its own control, reducing variability. However, the sample size was very small (only 8 pigs), which limits how much we can generalize the findings. The study measured actual nutrient absorption through intestinal samples rather than just estimating it, which is a strength. The research was published in a peer-reviewed journal, indicating it met scientific standards.
What the Results Show
Heating the plant-based feed (extrusion) significantly improved how much gross energy pigs could absorb compared to raw feed. The improvement was consistent across both the lower-protein and higher-protein diet versions. Heating also increased protein digestibility, meaning pigs could use more of the protein in the feed.
When enzymes were added after the heating process, the results improved even further. Pigs absorbed more nutrients from the E+A (extruded with enzymes added after) diets compared to just extruded diets alone. This suggests that the combination of heat treatment followed by enzyme addition works better than either method alone.
Interestingly, when enzymes were added before heating, the benefits were reduced or eliminated. Scientists believe this happened because the heat damaged the enzymes during the extrusion process, making them less effective. This finding suggests that timing matters—enzymes need to be added after heating to remain active and helpful.
The study found that essential amino acids (the building blocks of protein) were better absorbed when feed was heated, and this improvement was even greater when enzymes were added after heating. The standardized ileal digestibility of essential amino acids improved significantly with the E+A treatment. Both diet types (low and high protein) showed similar patterns of improvement, suggesting the processing methods work well regardless of the protein level in the feed.
Previous research has shown that plant-based ingredients contain anti-nutritional factors that reduce how well animals can digest them. This study confirms that heating helps break down these blocking compounds. The finding that enzyme addition improves results aligns with other research showing that specific enzymes can help break down plant fiber and other complex compounds. However, the finding that enzymes added before heating are less effective is a newer insight that adds to our understanding of how to best process plant-based feeds.
The study used only 8 pigs, which is a very small number. Results from such small studies may not apply to all pigs or all farming situations. The pigs were young and growing, so results might differ for adult pigs or pigs in different life stages. The study was conducted under controlled laboratory conditions, which may not reflect real farm environments. Additionally, the research doesn’t provide information about cost-effectiveness or long-term effects on pig health and growth rates, only nutrient absorption.
The Bottom Line
Based on this research, heating plant-based pig feed and adding enzymes afterward appears to improve nutrient absorption (moderate confidence level). Farmers interested in using peas and lentils as feed ingredients should consider using heat treatment followed by enzyme addition. However, larger studies on actual farms are needed before making major feed changes. Consult with a veterinarian or animal nutritionist before implementing these changes.
Pig farmers looking to reduce feed costs by using plant-based alternatives to soybean meal should pay attention to this research. Feed manufacturers developing sustainable products would find this relevant. Animal nutritionists and veterinarians advising on feed formulation should consider these findings. This research is less relevant for people feeding other animal species, as results may differ significantly.
If a farmer were to implement these feeding changes, improvements in nutrient absorption would likely occur immediately, as digestibility changes happen with each meal. However, visible improvements in pig growth and health would take weeks to months to become apparent. Long-term effects on overall farm profitability would require tracking over multiple production cycles.
Frequently Asked Questions
Does heating plant-based pig feed make it easier for pigs to digest?
Yes, research shows heating plant-based feed through extrusion significantly increases how much energy and protein pigs can absorb. Adding enzymes after heating improves results even further, making plant-based ingredients nearly as nutritious as traditional soybean meal.
What enzymes help pigs digest peas and lentils better?
The study tested a blend containing cellulase (breaks down plant fiber), xylanase (breaks down another type of fiber), protease (breaks down protein), and phytase (breaks down compounds that block mineral absorption). This combination worked best when added after heating.
Can farmers save money by feeding pigs peas and lentils instead of soybean meal?
Potentially yes, since peas and lentils are often cheaper than soybean meal. However, this study only measured nutrient absorption, not actual growth rates or farm profitability. Farmers would need to conduct their own cost-benefit analysis with proper heating and enzyme treatment.
Is this research ready to use on farms right now?
Not yet. The study used only 8 pigs under controlled conditions, which is too small to confidently recommend farm-wide changes. Larger studies on actual farms are needed to confirm these results work in real-world situations before widespread adoption.
Why did adding enzymes before heating reduce digestibility?
The heat from the extrusion process damaged the enzymes, making them less effective. Adding enzymes after heating keeps them intact and active, allowing them to break down plant compounds that block nutrient absorption.
Want to Apply This Research?
- Track weekly feed conversion ratio (pounds of feed needed to gain one pound of body weight) for pigs on plant-based diets versus traditional diets. Compare this metric monthly to identify cost savings and efficiency improvements.
- If managing a farm, users could test switching one pig group to heated and enzyme-treated plant-based feed while keeping another group on traditional feed, then compare growth rates and feed costs over 8-12 weeks using the app to log daily observations.
- Set up monthly reminders to weigh pigs, record feed consumption, and calculate feed efficiency. Track ingredient costs and compare total feed expenses between diet types. Monitor pig health indicators like activity level and coat condition to ensure the new feed supports overall wellness.
This research describes nutrient digestibility in pigs under controlled laboratory conditions with a very small sample size (8 animals). Results may not apply to all pig breeds, ages, or farm environments. Before making significant changes to pig feed formulations, consult with a veterinarian or animal nutritionist. This study measured nutrient absorption only and did not evaluate long-term health effects, growth rates, or economic viability on commercial farms. Individual results may vary based on specific farm conditions, pig genetics, and management practices.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.