How to ACIDIFY without acidifier ?

The acidification of the stomach serves as the first natural line of defense against bacterial contamination in the gut. This function is particularly crucial for piglets and chicks, as their ability to produce gastric acids is limited in early life. A well-acidified stomach not only helps with digestion through activation of pepsinogen enzyme and solubilization of minerals but also prevents pathogenic bacteria from reaching the intestines, reducing the risk of infections and improving overall gut health.

To support this process, various organic and inorganic acids are commonly incorporated into animal feed. Formic acid, propionic acid, citric acid, fumaric acid, and lactic acid are among the most widely used acidifiers. These acids effectively lower the pH in the stomach, creating an environment that inhibits harmful bacteria while enhancing nutrient absorption. However, their application is not without challenges. When used at inclusion rates of 10 to 15 kg per ton of feed, these acids often exhibit strong odors and corrosive properties, making handling and storage difficult for feed manufacturers.

In certain situations, such as when formulating premixes, manufacturers seek non-corrosive alternatives to achieve stomach acidification. This need has led to the adoption of an indirect acidification strategy, which focuses on lowering the Acid Binding Capacity (ABC) of the diet rather than directly introducing acids. By reducing the ABC of feed, it becomes easier for the piglet or chick's natural gastric acid secretion to maintain an optimal pH, without the drawbacks associated with traditional acidifiers.

The Role of Acid Binding Capacity in Feed Acidification

Acid Binding Capacity (ABC) measures the buffering effect of a diet—essentially, the amount of acid required to lower its pH to a target level. Ingredients with high ABC values require more acid to achieve the same pH reduction, placing a greater burden on the animal's digestive system and necessitating higher levels of dietary acidifiers.

Two ingredients commonly used in feed formulations that contribute significantly to high ABC values are calcium carbonate and zinc oxide. Calcium carbonate, with an ABC4 value of approximately +18,384 meq/kg, is a major contributor to diet buffering. Zinc oxide, traditionally used for its antibacterial properties in piglet diets, has an even higher ABC4 value of +21,863 meq/kg. These ingredients make it difficult to maintain a low stomach pH, particularly in young piglets with underdeveloped acid secretion.

Replacing High ABC Ingredients for Effective Indirect Acidification

To implement an effective indirect acidification strategy, it is essential to replace ingredients with high ABC values with alternatives that contribute to a more favorable gastric environment. Two of the most effective replacements are calcium formate and activated zinc oxide.

Calcium Formate Calcium formate serves as an excellent alternative to calcium carbonate. Unlike calcium carbonate, which has a strong buffering effect, calcium formate has a much lower ABC4 value, making it easier for the stomach to maintain an acidic environment. Additionally, calcium formate provides the additional benefit of releasing formate salt, which have been shown to possess antimicrobial properties, further supporting gut health and pathogen control in piglets and chicks.

Activated Zinc Oxide While zinc oxide has long been used in piglet diets for its antibacterial properties, its high ABC value makes it counterproductive to stomach acidification. However, an alternative known as activated zinc oxide provides a solution. Activated zinc oxide possesses a 10-fold higher specific surface area compared to traditional zinc oxide, allowing for a significant reduction in the required dosage—by as much as 6 to 10 times. This improved bioavailability means that the same antimicrobial benefits can be achieved with a fraction of the amount, all while minimizing its impact on diet buffering capacity.

The table below is illustrating 3 different strategies to reduce the pH of a Swine or Poultry diet (expressed in meq of ABC4) The strategy 1 is the standard approach consisting in incorporating acidifiers. The addition of 1kg of a formic acid in powder form (sprayed on silica) will reduce the diet of 8 meq per ton. To bring the diet from 400 meq which is a standard level in Asia down to the 250 meq that we should target for piglets and chicks diets, that will require the incorporation of more than 18kg for an average cost of 27 USD per ton which is difficult to implement. 

This table confirms as well that the indirect acidification strategies, namely the strategy 2 and 3 can be cheaper (4 to 20 times cheaper) and even more effective than the direct strategy.

But there is a limit to the strategy 2 and 3 as there is a limited quantity of calcium carbonate and zinc oxide to replace. Therefore, the most economical solution to reduce the ABC4 of a piglet diet by 150meq / ton would be a mix of the 3 strategies as illustrated below.

This plan would cost a total of 8.7 USD for an impact of 150meq per ton of feed. It would cost 3 times more to get the same effect by using only acidifiers.

For Poultry, only the combination of strategy 2 and 1 would be relevant but the targeted reduction of ABC4 may be lower so we may end up with a similar cost.

Morever, there are other benefits in combining these 3 strategies as the reduction of zinc oxide would also positively affect the feed intake, the feed contamination in heavy metals, the neutralization of phytase enzymes as well the prevention of antibiotic resistance coming from high dosage of zinc oxide.

Conclusion

Indirect acidification presents a practical and non-corrosive approach to optimizing gastric pH in piglets and chicks. By focusing on lowering the Acid Binding Capacity of the diet rather than introducing large quantities of acids, feed manufacturers can achieve effective acidification without the handling challenges associated with organic acid supplementation. The strategic replacement of calcium carbonate with calcium formate and the substitution of traditional zinc oxide with activated zinc oxide offer viable solutions to this challenge. As the industry continues to seek safer and more efficient ways to enhance gut health in young animals, indirect acidification stands out as a promising alternative that aligns with both nutritional and practical considerations.

David SERÈNE