Acidifiers and organic acids in livestock nutrition and health

For many years, antibiotics were used in feed to improve animal performance. However, the accelerated adverse effects of antibiotics on animal health and products and the banning of in-feed antibiotics as feed additives make the exploration of safe alternate antibiotic-free growth promoters a premium area of research. Probiotics, prebiotics, phytochemicals, enzymes, organic acids, and inorganic acids are candidate alternatives. Ruminal acidifiers include inorganic and organic acids, which play important roles in altering ruminal fermentation, feed digestion, and animal performance and health. Inorganic acid administration is not joint in livestock production, while organic acids are promising feed additives that can replace antibiotics in animal feeds. Organic acids manipulate the beneficial intestinal microbes, reduce pathogenic bacteria, and improve animal immunity. Organic acids also alter the ruminal microbial population and improve the digestibility and absorption of nutrients by facilitating digestive enzyme secretion and increasing feed retention time in the digestive system. Organic acids cause changes in the intestinal lining, making it thinner, and facilitating nutrient absorption and utilization. However, this effect was not observed with all types of organic acids, depending on the pKa value of each one. The effect of organic or inorganic acids supplementation depends on the type, concentration level, growth phase, health status of animals, hygienic standards, and environmental factors. There are claims about neutralizing the in-feed organic acids in the intestine by the secretion of bicarbonates. Moreover, organic acids react with metallic items in feed mills and reduce palatability due to their bitter taste. This chapter highlights the role of different acidifiers, mainly organic acids, in ruminant nutrition, with emphasis on their ability to improve ruminal fermentation, nutrient digestibility, performance, milk and meat quality, and animal health status.