Research shows that adding a mixture of two beneficial bacteria to lower-protein pig feed increases growth speed by 12-14% and reduces feed waste by 11-12%, while simultaneously cutting nitrogen pollution from pig farms. According to Gram Research analysis of this 180-pig study, the bacteria supplement allows farmers to maintain productive pig growth while using environmentally friendlier feed formulations, with the added benefit of producing more tender, higher-quality meat.
Researchers found that adding two types of beneficial bacteria to pig feed can help animals grow faster and stronger while using less feed—even when the feed has less protein than normal. According to Gram Research analysis, this discovery matters because it could help pig farms reduce pollution from nitrogen waste while keeping pigs healthy and productive. The study tested 180 pigs over 49 days and found that pigs getting the bacteria supplement grew 12-14% faster and converted feed to meat more efficiently than pigs on regular low-protein diets.
Key Statistics
A 2026 research study of 180 finishing pigs found that supplementing low-protein feed with Bacillus subtilis and Lactobacillus acidophilus increased average daily weight gain by 12-14% compared to unsupplemented low-protein diets.
Pigs receiving the beneficial bacteria supplement required 11-12% less feed to gain the same amount of weight compared to pigs on low-protein diets without the supplement, according to a 49-day study published in the Journal of the Science of Food and Agriculture.
The bacteria supplement reduced ammonia emissions and fecal nitrogen content by significant amounts in finishing pigs, while simultaneously improving meat tenderness and fat content compared to standard protein diets.
Genetic analysis revealed that the bacteria supplement enriched beneficial microbial populations and activated metabolic pathways related to nitrogen metabolism and amino acid transport in pig digestive systems.
The Quick Take
- What they studied: Whether adding a special mix of two beneficial bacteria (Bacillus subtilis and Lactobacillus acidophilus) to lower-protein pig feed could help pigs grow better and reduce harmful nitrogen pollution
- Who participated: 180 young pigs (crossbred Duroc × Landrace × Yorkshire) weighing about 220 pounds each at the start, divided into three groups and fed different diets for 49 days
- Key finding: Pigs fed low-protein diet with the bacteria supplement grew 12-14% faster and needed 11-12% less feed to gain the same weight compared to pigs on regular low-protein feed without the bacteria
- What it means for you: If you work in pig farming or care about sustainable food production, this suggests that beneficial bacteria can help farms reduce environmental pollution while maintaining profitable pig growth. However, this is one study in pigs and would need testing in other settings before widespread adoption
The Research Details
Scientists divided 180 finishing pigs into three equal groups. One group ate normal feed with standard protein levels (the control group). A second group ate feed with 20% less protein (the low-protein group). The third group ate the same low-protein feed but with an added supplement containing two types of beneficial bacteria that work together. All pigs were monitored for 49 days while researchers measured how fast they grew, how much feed they ate, and how much nitrogen waste they produced.
The researchers chose this design because low-protein diets are known to reduce nitrogen pollution from pig farms, but they can sometimes slow pig growth. By adding beneficial bacteria, they wanted to see if they could get the best of both worlds: environmental benefits without sacrificing pig performance.
After the study ended, scientists analyzed the pigs’ gut bacteria using advanced genetic testing to understand how the beneficial bacteria changed the microbial community and improved nitrogen processing in the pigs’ digestive systems.
This research approach is important because it tests a practical, real-world solution that pig farmers could actually use. Rather than just studying bacteria in a lab, the researchers tested it in living animals over a realistic production timeline. The genetic analysis of gut bacteria helps explain the ‘why’ behind the results, making the findings more credible and useful for future applications
This study has several strengths: it used a large sample size (180 pigs), included a proper control group for comparison, randomly assigned pigs to groups, and measured multiple important outcomes (growth, feed efficiency, pollution, meat quality, and gut bacteria). The study was published in a peer-reviewed scientific journal. However, the study was conducted in one location with one pig breed, so results might differ in other settings or with different pig types. The study lasted only 49 days, so long-term effects are unknown
What the Results Show
Pigs receiving the bacteria supplement on low-protein feed grew significantly faster than pigs on regular low-protein feed without the supplement. Specifically, they gained 12-14% more weight per day and required 11-12% less feed to produce the same amount of meat. This is important because it means farmers could use less feed (saving money) while still getting good pig growth.
The bacteria supplement also dramatically reduced environmental pollution. Pigs in the bacteria group produced less ammonia gas, had lower nitrogen levels in their blood, and produced less nitrogen waste in their manure. These improvements matter because nitrogen pollution from pig farms contributes to water contamination and air quality problems.
Interestingly, all pigs on low-protein diets (with or without bacteria) produced meat that was more tender and had more fat marbling—the small streaks of fat throughout the muscle that make meat taste better. This was an unexpected bonus that could improve meat quality for consumers.
Genetic analysis of the pigs’ gut bacteria revealed that the beneficial bacteria supplement changed the microbial community in helpful ways. The supplement increased populations of bacteria called Prevotella and Porphyromonadaceae, which are associated with better nutrient processing. The bacteria also activated metabolic pathways related to nitrogen handling, energy production, and amino acid transport—essentially improving the pigs’ ability to use nutrients efficiently from their feed
Previous research showed that low-protein diets reduce nitrogen pollution but can slow pig growth. This study builds on that knowledge by showing that strategic use of beneficial bacteria can overcome the growth slowdown while maintaining the environmental benefits. The findings align with growing evidence that probiotics and fermented supplements can improve animal performance, but this is one of the first studies to demonstrate this synergy specifically in low-protein pig diets
The study was conducted with only one breed of pigs in one location, so results might differ with other pig types or in different environments. The 49-day study period covers only the finishing phase of pig production, so it’s unclear if benefits would continue longer or apply to younger pigs. The study didn’t test different doses of the bacteria supplement, so the optimal amount is unknown. Finally, the research was conducted in a controlled research setting, and real-world farm conditions might produce different results
The Bottom Line
For pig farmers: Consider supplementing low-protein diets with this type of beneficial bacteria mixture if environmental regulations or sustainability goals are important to your operation. The evidence is strong (from a controlled study) that it improves growth and reduces pollution, but test it on a small scale first before converting entire herds. For consumers: This research supports choosing pork from farms using sustainable practices, as these methods can produce quality meat while reducing environmental impact. Confidence level: Moderate—this is solid research but limited to one study in one setting
Pig farmers focused on sustainability or operating in areas with strict nitrogen pollution regulations should pay close attention to these findings. Feed manufacturers and agricultural companies might consider developing similar products. Environmental advocates and consumers interested in sustainable food production should find this encouraging. This research is less relevant to small-scale or hobby pig farmers, or those in regions without environmental concerns about nitrogen pollution
Based on this study, benefits would appear within the first few weeks of supplementation. The 49-day study period showed consistent improvements throughout, suggesting that farmers would see faster growth and reduced pollution relatively quickly after starting the supplement. However, long-term effects beyond 49 days are unknown
Frequently Asked Questions
Can beneficial bacteria help pigs grow faster on lower-protein feed?
Yes. A 2026 study of 180 pigs found that supplementing low-protein feed with Bacillus subtilis and Lactobacillus acidophilus increased growth by 12-14% and improved feed efficiency by 11-12% compared to unsupplemented low-protein diets, while also reducing nitrogen pollution.
Does reducing protein in pig feed hurt meat quality?
No. Pigs on low-protein diets actually produced more tender meat with better fat marbling compared to standard-protein diets. When combined with the bacteria supplement, pigs maintained excellent growth while producing higher-quality meat.
How much does nitrogen pollution decrease with this bacteria supplement?
The study showed significant reductions in ammonia emissions, serum urea nitrogen, and fecal nitrogen content in pigs receiving the bacteria supplement compared to those on low-protein feed alone, though specific percentage reductions varied by measurement type.
Is this bacteria supplement safe for pigs?
The study showed no adverse effects in the 180 pigs tested over 49 days. Both Bacillus subtilis and Lactobacillus acidophilus are naturally occurring bacteria commonly used in animal feed, though long-term safety data beyond this study period is limited.
Would this work for all types of pigs or just finishing pigs?
This study tested only finishing pigs (young pigs near market weight) for 49 days. Results might differ for younger pigs or in different production phases, so additional research would be needed to confirm effectiveness across all pig types and ages.
Want to Apply This Research?
- Track daily weight gain and feed conversion ratio (pounds of feed needed per pound of weight gained) weekly. Compare these metrics before and after introducing the bacteria supplement to quantify the improvement on your farm
- If managing a pig farm, implement a trial period using the bacteria supplement on a subset of pigs while maintaining control groups. Log feed purchases, pig weights, and manure characteristics to measure real-world impact on your specific operation
- Establish baseline measurements of pig growth rates, feed costs, and nitrogen emissions before supplementation. After introducing the supplement, track the same metrics monthly for at least 3-6 months to determine if the 12-14% growth improvement and reduced pollution hold true in your specific farming conditions
This research describes findings from a single 49-day study in finishing pigs and should not be considered definitive guidance for all farming operations or pig types. Results may vary based on pig breed, farm conditions, feed formulation, and environmental factors. Farmers considering implementing these findings should consult with veterinarians and animal nutritionists familiar with their specific operations. This information is for educational purposes and does not constitute professional agricultural or veterinary advice. Always follow local regulations regarding feed additives and animal care practices.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.