Research shows that reducing the acid-binding capacity of low-zinc diets significantly improves growth and reduces diarrhea in newly weaned piglets, recovering most of the performance loss from removing pharmaceutical zinc oxide. According to Gram Research analysis of a 2026 study of 1,445 piglets, gradually reducing diet acidity through ingredient changes and acid additives during the first three weeks after weaning helped piglets grow nearly as well as those receiving pharmaceutical zinc, while substantially decreasing digestive problems.
When piglets are weaned from their mothers, they often get sick and stop growing well. Farmers usually add a special form of zinc called zinc oxide to prevent this problem. But according to Gram Research analysis, a new study found that adjusting how acidic a piglet’s diet is can help them grow better even without the zinc medicine. Researchers fed 1,445 newly weaned piglets different diets and discovered that making the diet less alkaline (more acidic) by changing ingredients and adding acids helped the piglets gain weight faster and get diarrhea less often. This discovery could help farmers raise healthier piglets without relying on pharmaceutical zinc.
Key Statistics
A 2026 study of 1,445 weaned piglets in a commercial farm found that reducing dietary acid-binding capacity from 326 to 150 meq H+/kg in phase 1 significantly improved growth performance and reduced diarrhea prevalence compared to high acid-binding capacity low-zinc diets.
Research showed that piglets fed low-zinc diets with reduced acid-binding capacity achieved growth rates and feed efficiency substantially closer to pharmaceutical zinc-supplemented diets, with the most acidic treatment showing the greatest recovery of performance.
In the 2026 trial of 1,445 piglets, reducing diet acid-binding capacity during the first three weeks after weaning produced lasting benefits that persisted even after all piglets were switched to a common diet at day 21.
The Quick Take
- What they studied: Whether changing how acidic piglet feed is can help them grow better and stay healthier after weaning, even without pharmaceutical zinc supplements.
- Who participated: 1,445 newly weaned piglets weighing about 5 kilograms each in a commercial farm setting. The piglets were divided into groups receiving different diet treatments over three weeks.
- Key finding: Piglets fed diets with reduced acid-binding capacity (meaning more acidic diets) without pharmaceutical zinc grew significantly better and had less diarrhea compared to piglets on low-zinc diets with high acid-binding capacity. The improvement was substantial enough to partly recover the growth loss normally seen when pharmaceutical zinc is removed.
- What it means for you: If you raise pigs commercially, this suggests you may be able to reduce or eliminate pharmaceutical zinc oxide from weaned piglet diets by adjusting diet acidity instead. This could lower costs and reduce antibiotic use. However, results are from one study in a specific farm setting, so consult with a veterinarian before making major diet changes.
The Research Details
Researchers conducted a controlled feeding trial with 1,445 newly weaned piglets in a real commercial farm environment. The piglets were randomly assigned to five different diet groups during the first two weeks after weaning (called phase 1 and phase 2). One group received the standard high-zinc diet with pharmaceutical zinc oxide, while four other groups received low-zinc diets with gradually decreasing acidity levels. The researchers changed the acidity by swapping ingredients: replacing certain soybean products with low-acid soy protein, replacing limestone with calcium formate, and adding formic and benzoic acids. All diets were carefully balanced to have the same energy content and essential nutrients except for zinc and acidity levels.
After the first three weeks, all piglets were fed the same standard diet for the remaining three weeks of the study. The researchers measured how much the piglets grew, how much feed they ate, how efficiently they converted feed to body weight, and how often they developed diarrhea. They used statistical analysis to determine whether differences between groups were real or just due to chance.
This approach is valuable because it tests the idea in a real farm setting rather than a laboratory, which means the results are more likely to work in actual pig farming operations. The large number of piglets (1,445) also makes the findings more reliable and less likely to be due to random variation.
This research matters because pharmaceutical zinc oxide has been a standard tool for preventing post-weaning problems in piglets for decades. However, there is growing concern about using high doses of medications in animal feed. Finding alternative methods that work just as well could help farmers reduce pharmaceutical use while maintaining pig health and growth. The study’s focus on diet acidity is novel because it targets the underlying digestive chemistry rather than just adding more zinc.
The study’s strengths include a large sample size (1,445 piglets), a real commercial farm setting, careful control of diet composition to isolate the effect of acidity, and measurement of multiple outcomes (growth, feed efficiency, and diarrhea). The main limitation is that this was conducted in one specific farm environment, so results may vary in different farms with different conditions, management practices, or pig genetics. The study does not explain the biological mechanism explaining why reduced acidity helps, which would strengthen confidence in the findings. Additionally, the long-term effects beyond 42 days were not measured.
What the Results Show
Removing pharmaceutical zinc oxide from weaned piglet diets significantly reduced growth performance and increased diarrhea prevalence during the first three weeks after weaning, as expected based on previous research. However, when researchers gradually reduced the acid-binding capacity of the low-zinc diets (making them more acidic), they observed substantial improvements. Piglets on the most acidic low-zinc diet showed growth rates and feed efficiency that were much closer to the high-zinc control group than piglets on high acid-binding capacity low-zinc diets.
The reduction in diarrhea was particularly striking. Piglets fed diets with low acid-binding capacity had significantly fewer cases of diarrhea compared to those on high acid-binding capacity diets without pharmaceutical zinc. This suggests that diet acidity directly influences gut health in newly weaned piglets. The improvements were consistent across both phase 1 (days 0 to 7) and phase 2 (days 7 to 21), indicating that the effect was reliable during the critical post-weaning period.
By day 42, when all piglets were eating the same diet, the differences between groups had largely disappeared, suggesting that the early diet modifications had lasting benefits without requiring continued special feeding. This is important because it means farmers would only need to adjust diets during the vulnerable first three weeks after weaning.
The study found that the specific dietary changes used to reduce acid-binding capacity (replacing enzymatically-treated soybean meal with low-acid soy protein concentrate, replacing limestone with calcium formate, and adding formic and benzoic acids) were practical and could be implemented in commercial feed mills. The researchers maintained all other important nutrients at consistent levels, which means the improvements were specifically due to the acidity changes rather than other nutritional factors. This careful control strengthens confidence that diet acidity is the key factor.
This research builds on decades of knowledge showing that pharmaceutical zinc oxide prevents post-weaning problems in piglets. The novelty is demonstrating that modifying diet acidity can partially replace this pharmaceutical approach. Previous research has suggested that acidifying diets might help piglet digestion, but this is one of the first large-scale commercial studies showing the magnitude of benefit when acidity is systematically reduced in low-zinc diets. The findings align with growing interest in reducing pharmaceutical use in animal agriculture while maintaining productivity.
The study was conducted in a single commercial farm environment, so results may not apply to all farms with different conditions, management styles, or pig genetics. The researchers did not measure the biological mechanisms explaining why reduced acidity helps, such as changes in gut bacteria or digestive enzyme activity. The study only measured outcomes up to 42 days of age, so long-term effects on adult pig performance are unknown. Additionally, the study did not compare the cost of the dietary modifications to the cost of pharmaceutical zinc, which would be important for farmers deciding whether to make the change. Finally, the specific diet ingredients used (wheat and barley based) may limit how well results apply to farms using different grain sources.
The Bottom Line
Based on this research, commercial pig farmers may consider gradually reducing diet acid-binding capacity in weaned piglet diets as a partial replacement for pharmaceutical zinc oxide during the first three weeks after weaning. This approach appears to recover most of the growth performance loss and significantly reduce diarrhea. However, confidence in this recommendation is moderate because the study was conducted in one farm setting. Before implementing this change, farmers should consult with their veterinarian and nutritionist to ensure the dietary modifications work in their specific operation. Start with a small trial before making farm-wide changes.
Commercial pig farmers and feed manufacturers should pay attention to these findings, as they offer a practical alternative to pharmaceutical zinc supplementation. Veterinarians advising pig producers would benefit from understanding this approach. Consumers interested in reducing pharmaceutical use in animal agriculture may also find this relevant. However, small-scale or hobby pig farmers may not see the same benefits if their management practices differ significantly from the commercial farm where this study was conducted.
Improvements in growth and diarrhea reduction appeared within the first week after weaning and were consistent through the third week. Farmers should expect to see benefits relatively quickly if they implement these dietary changes, typically within 7 to 14 days. However, the full effect on overall farm productivity and economics may take longer to assess, as it depends on factors like feed costs and long-term pig health.
Frequently Asked Questions
Can I stop using zinc oxide in piglet feed if I make the diet more acidic?
Research suggests you can partially replace pharmaceutical zinc by reducing diet acid-binding capacity, but not completely eliminate it. A 2026 study found that acidified low-zinc diets recovered most growth performance loss and significantly reduced diarrhea, though results were not identical to pharmaceutical zinc supplementation. Consult your veterinarian before making changes.
How do I make piglet feed more acidic without special equipment?
The study achieved this by replacing enzymatically-treated soybean meal with low-acid soy protein concentrate, replacing limestone with calcium formate, and adding formic and benzoic acids. These are standard feed ingredients available through commercial feed suppliers and can be incorporated during normal feed mill operations.
How long does it take to see improvements in piglet growth and health?
Improvements in growth rate and diarrhea reduction appeared within the first week after weaning and remained consistent through week three. Farmers should expect to observe benefits relatively quickly, typically within 7 to 14 days of implementing the dietary changes.
Will this work on my farm if I use different grains or management practices?
This study was conducted on one commercial farm using wheat and barley-based diets, so results may vary with different ingredients, farm conditions, or management practices. Start with a small trial on your farm before making farm-wide changes, and work with your veterinarian to adapt the approach to your specific situation.
What is acid-binding capacity and why does it matter for piglets?
Acid-binding capacity measures how much acid a diet can neutralize in the piglet’s stomach and digestive system. Lower acid-binding capacity means the diet is more acidic, which appears to improve digestion and gut health in newly weaned piglets, reducing diarrhea and improving growth even without pharmaceutical zinc supplementation.
Want to Apply This Research?
- Track daily weight gain and diarrhea incidence in weaned piglet groups fed with reduced acid-binding capacity diets versus control diets. Measure and log average daily gain (in grams per day) and percentage of piglets with diarrhea each day for the first 21 days after weaning.
- If managing a pig farm, implement a trial period where you gradually introduce the acidified diet (using the specific ingredient swaps described: soy protein concentrate, calcium formate, and added acids) to one group of newly weaned piglets while keeping a control group on standard diet. Compare growth and health outcomes over three weeks.
- Use the app to record feed intake, weight measurements, and health observations (diarrhea cases) for each piglet group daily. Create a comparison dashboard showing growth curves and diarrhea rates between the acidified diet group and control group. Track feed costs and calculate the return on investment from any productivity improvements.
This research describes findings from a single commercial farm study and should not be considered a substitute for professional veterinary or nutritional advice. Before making changes to piglet diets, consult with a veterinarian and animal nutritionist familiar with your specific farm conditions, genetics, and management practices. Results may vary based on farm environment, feed ingredients, and piglet genetics. This information is for educational purposes and does not constitute medical or veterinary guidance. Always follow local regulations regarding animal feed and pharmaceutical use.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.