pH value worked as an important element in animal digestive system. While the pH value around 2~2.5 in stomach and 5~7 in small intestine, the nutrients in fodder can be digested completely, the beneficial bacteria can grow properly and pathogenic microbes can be controlled effectively. Animal growth property, feed efficiency and antiviral ability can be improved by controlling the acidic environment inside animals.
However as the digestive system in young animals is not well-developed, the gastric acid secretion is insufficient, digestive enzyme activity is low and pH in gastrointestinal tract is too high for the digestive enzyme activity and growth of beneficial bacteria. Acidifiers used in animal fodder can lower the pH in digestive system, thus providing the best environment for digestion, nutrient intake and resistance to disease. Acidifiers have become very important additives in animal feed after antibiotics, probiotics and enzymic products. Acidifiers may not be possible to take full place of antibiotics, but certainly they can work as substitute for some medicated premix.
The mechanism of feed acidifiers
Acidifiers can lower pH in animal feed and stomach contents, thus improve the activity of digestive ferment. Adding 1.5% of Calcium formate in animal feed can lower the pH of feed by 0.5. 1% of Calcium formate and 0.5% of propionic acid added into animal feed can lower the pH by 0.7 in feed. Research also shows that 1% of calcium formate and 1.5% of citric acid added in animal feed can lower pH by 0.18 and 0.34 respectively. 1.5% of Citric acid and 1.5% of fumaric acid used in daily diet of piglets can lower feed pH from 6.42 to 3.82 and 3.87 respectively, and lower pH in stomach contents from 4.07 to 3.82 and 3.87 respectively. This means acidifiers can lower pH in stomach contents to some extent.
To early weaned piglets, the gastric acid secretion is insufficient and pH in fodder is between 5.8 to 6.5, which causes the pH value higher than best activity pH range for pepsase. The digestion and nutrient absorption of fodder is affected. Organic acid added in piglet fodder can improve the growth properties. According to statistics, adding 1.5-2.0% of fumaric acid into feed can increase average daily gain by 9%, feed consumption by 5.2% and feed efficiency by 4.4%.
The kinds and dose of acidifiers used in animal feed
World recognized efficient acidifiers include citric acid, fumaric acid and calcium formate, while propionic acid, butyric acid, malic acid, hydrochloric acid or sulfuric acid have non-efficiency and even negative effect as proved by lots of experiments. In regard to daily gain and feed efficiency, the effects of citric acid, fumaric acid and calcium formate are: citric acid> fumaric acid> calcium formate. The effects and doses are different with different acidifiers. It is believed that proper dose of acidifiers can exert positive effect. Underdosage cannot lower pH in digestive system and overdosage may affect feed palatability. Generally, the dose added into feed should be 0.5%-3.0%.