Abstract
Due to the increasing safety concerns about the risk of spreading antibiotic resistance in the environment, and the presence of chemical residues in animal products, using organic acids (OAs) to replace antibiotic in the diet of farm animals has increased considerably in recent years. It has been suggested that OAs could attribute to diverse elements such as antimicrobial activity, decreasing the pH of digesta particularly in the gastrointestinal tract (GIT), slowing feed transit in the GIT to maximize feed digestion and nutrient absorption, inducing enzyme secretion and activity in the small intestine, and providing nutrients to intestinal tissue. It has been reported that OAs mixture might be more effective than individual OAs due to the synergistic effects of different pKa values and have a broad-spectrum activity. In conclusion, this review showed that an OA mixture, which can improve nutrient digestibility and growth performance, modulate intestinal bacterial populations and improve gut health, as well as decreasing gas emission, can be used as alternative to antibiotic growth promoters. However, the results of OA mixtures are not always consistent, and the response to dietary OAs could be affected by the type of OAs, dosage, feed formula, and the age of animals. In this review, we will give an overview of the current use of OAs mixture in swine feed.