Research shows that fermenting soybean waste (okara) with beneficial bacteria and rice bran creates a nutritious chicken feed ingredient that improves gut health. According to Gram Research analysis of a 2026 study with 112 broiler chickens, adding 2.5% of this fermented mixture to feed maintained normal feed efficiency while increasing intestinal lining thickness, a marker of better digestive health. The fermentation process breaks down proteins and increases helpful bacteria in the chicken’s digestive system.
Scientists discovered that fermenting okara (leftover soybean pulp) with beneficial bacteria and rice bran creates a nutritious chicken feed ingredient. According to Gram Research analysis, when chickens ate feed containing 2.5% of this fermented mixture, they had better gut health and improved intestinal lining thickness compared to regular feed. The fermentation process breaks down proteins and creates helpful compounds that chickens can digest more easily. This research shows how food waste can be transformed into valuable animal nutrition while supporting chicken health.
Key Statistics
A 2026 research study of 112 broiler chickens found that fermented okara and rice bran at 60% moisture fermented for 72 hours increased lactic acid production and degraded major soybean storage proteins, making nutrients more available to animals.
In broiler chickens fed 2.5% fermented okara and rice bran mixture, ileal villus height increased compared to control birds, indicating improved intestinal structure for better nutrient absorption.
Fermentation reduced harmful Proteobacteria genera (Pantoea, Pseudomonas, and Enterobacter) while increasing beneficial Lactobacillus and Streptococcus bacteria in the fermented ingredient.
Chickens fed 1.25% and 2.5% fermented okara and rice bran showed increased abundance of Romboutsia timonensis, a carbohydrate-utilizing bacterium that enhances substrate utilization in the digestive system.
The Quick Take
- What they studied: Whether fermenting soybean waste (okara) with healthy bacteria and rice bran creates better chicken feed, and at what amount it works best.
- Who participated: 112 one-day-old broiler chickens (the type raised for meat) divided into groups eating different amounts of the fermented ingredient.
- Key finding: Chickens fed 2.5% fermented okara and rice bran mixture maintained normal feed efficiency while developing thicker, healthier intestinal linings compared to control chickens.
- What it means for you: This research could help chicken farmers use food waste more efficiently while improving bird health. For consumers, it may eventually mean more sustainable and healthier chicken production, though this is early-stage research focused on the farming side.
The Research Details
The scientists conducted two separate experiments. In the first experiment, they mixed okara (the leftover pulp from making soy milk) with rice bran and added three types of beneficial bacteria called Lactobacillus. They tested different moisture levels (how wet the mixture was) and fermentation times to find the best conditions. They discovered that 60% moisture and 72 hours of fermentation worked best, creating more lactic acid (a natural preservative) and breaking down soybean proteins into simpler forms.
In the second experiment, they fed 112 young broiler chickens either regular feed or feed containing different amounts (1.25%, 2.5%, or 5%) of the fermented mixture. They then analyzed the chickens’ gut bacteria, intestinal health, and chemical compounds in their digestive systems to understand how the fermented ingredient affected them.
This approach is important because it combines practical farming concerns (making good feed) with scientific analysis (understanding exactly what happens in the chicken’s body) to ensure the ingredient is both effective and safe.
Understanding how fermentation changes food waste into usable animal feed is crucial for sustainable agriculture. By using scientific analysis of bacteria and chemical compounds, researchers can determine the exact amount that benefits chickens without causing problems. This prevents guesswork and ensures the ingredient works as intended.
The study used multiple scientific methods to verify results: they analyzed the bacteria present, measured chemical compounds produced, examined intestinal tissue under microscopes, and used computational methods to predict how the bacteria function. Testing on 112 animals provides reasonable confidence in the findings. The research was published in Poultry Science, a peer-reviewed journal, meaning other experts reviewed the work before publication. However, the study focused on one chicken breed in controlled conditions, so results may vary in different farming situations.
What the Results Show
The fermentation process successfully transformed okara into a more digestible ingredient. When fermented at 60% moisture for 72 hours, the mixture showed increased lactic acid production and breakdown of major soybean proteins, making nutrients more available to chickens.
When chickens ate feed containing 2.5% of the fermented mixture, they maintained the same feed conversion ratio (meaning they gained weight as efficiently as control chickens) while developing thicker intestinal linings. Thicker intestinal linings are important because they help chickens absorb nutrients better and resist disease.
The gut bacteria in chickens eating the fermented ingredient changed in beneficial ways. A helpful bacteria called Romboutsia timonensis increased in chickens eating 1.25% and 2.5% of the fermented mixture. This bacteria specializes in breaking down carbohydrates, which helps chickens extract more energy from their food.
Chemical analysis showed that the fermented ingredient enhanced amino acid and sulfur-related pathways in the chickens’ digestive systems at the 1.25% and 2.5% inclusion levels, suggesting improved nutrient processing.
The fermentation process reduced harmful bacteria (Proteobacteria) that can cause disease, while increasing beneficial bacteria like Lactobacillus and Streptococcus. At the 2.5% inclusion level, the fermented ingredient produced the broadest range of beneficial metabolic changes in the chickens’ digestive systems. However, at the highest level tested (5% of the diet), fewer beneficial changes were observed, suggesting there’s an optimal amount to use.
This research builds on existing knowledge that fermentation improves animal feed quality. Previous studies showed that fermenting plant-based ingredients makes proteins more digestible. This study advances that understanding by showing exactly how fermentation with specific bacteria and rice bran affects both the ingredient itself and the chicken’s digestive system. The finding that 2.5% is optimal is practical information that previous research hadn’t established.
The study used only one chicken breed (Arbor Acres broilers) in controlled laboratory conditions, so results may differ with other breeds or in typical farm environments. The research lasted only through the broiler growth period, so long-term effects are unknown. The study didn’t measure final meat quality or taste, only digestive health markers. Additionally, the exact mechanisms explaining why 2.5% works better than 5% need further investigation. Results are specific to this fermentation method and may not apply to other fermentation approaches.
The Bottom Line
Based on this research, adding 2.5% fermented okara and rice bran mixture to broiler chicken feed appears safe and beneficial for intestinal health (moderate confidence level). This recommendation applies specifically to broiler chickens and the fermentation method described. Farmers interested in trying this should start with small-scale trials before full implementation. Further research is needed before recommending this for other poultry types or in commercial farm settings.
Chicken farmers and feed manufacturers should pay attention to this research as a potential way to use food waste sustainably while improving bird health. Consumers interested in sustainable food production may find this relevant. This research is NOT directly applicable to human nutrition, though it demonstrates how fermentation can improve food ingredient quality. Pet owners with chickens might find this interesting but should consult with veterinarians before changing feed.
Based on the study design, improvements in intestinal health appeared within the broiler growth period (typically 6-7 weeks). Farmers would likely see changes in chicken health markers within 2-4 weeks of switching to the fermented ingredient, though individual results may vary.
Frequently Asked Questions
Can fermented soybean waste be used as chicken feed?
Yes, research shows fermented okara (soybean waste) mixed with rice bran can be used as a chicken feed ingredient. A 2026 study found that 2.5% inclusion in broiler feed maintained feed efficiency while improving intestinal health markers.
What percentage of fermented okara should be added to chicken feed?
According to 2026 research with 112 broiler chickens, 2.5% fermented okara and rice bran mixture in feed produced the best results, including improved intestinal lining thickness and beneficial changes in gut bacteria without reducing feed efficiency.
How does fermentation improve animal feed quality?
Fermentation with beneficial bacteria like Lactobacillus breaks down complex proteins into simpler forms that animals can digest more easily. It also increases lactic acid production and reduces harmful bacteria while promoting beneficial digestive bacteria.
Does fermented soybean waste affect chicken meat quality?
This study measured intestinal health improvements but did not evaluate final meat quality or taste. Further research is needed to determine if these digestive improvements translate to better meat quality or other consumer-relevant outcomes.
Is fermented okara safe for all chicken types?
This research tested only broiler chickens (meat-type birds) in controlled conditions. Safety and effectiveness for other chicken breeds, laying hens, or backyard flocks has not been established and would require additional research.
Want to Apply This Research?
- For farmers using this ingredient: track weekly feed conversion ratio (pounds of feed per pound of weight gain), monitor chicken health observations (activity level, feather quality, mortality), and record any digestive issues. Compare these metrics between control and treatment groups.
- Farmers could implement a gradual transition protocol: start by replacing 1.25% of regular feed with the fermented mixture for one flock, measure results, then increase to 2.5% for the next flock if results are positive. Document feed costs, chicken performance, and health outcomes.
- Establish a baseline with current feed for 2-3 flocks, then introduce the fermented ingredient at 2.5% inclusion for 3-4 flocks while tracking the same metrics. Compare average performance between baseline and treatment groups. Adjust based on local conditions and results.
This research describes an experimental animal feed ingredient tested in controlled laboratory conditions with one chicken breed. These findings are not yet standard farming practice and should not be implemented without consulting with a poultry nutritionist or veterinarian. Results may vary significantly based on local conditions, chicken breed, farm management practices, and feed formulation. The study did not evaluate long-term effects, meat quality, or safety in commercial farm settings. Anyone considering implementing this ingredient should conduct small-scale trials first and monitor bird health closely. This research is about animal nutrition only and has no direct application to human food or health.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.