Biological Function of Condensed Tannins and Their Application in Animal Production

Condensed tannins (CT) are polyphenolic polymers that are plant secondary metabolites acting as important component in plant chemical defense system against pathogenic, virus and insect invasion. Tannins have many physiological effects such as antioxidation, anti-inflammation, antimicrobial, anti-parasite and anti-virus. Tannins have been regarded as “anti-nutritional factors” due to their antifeedant and digestion-inhibiting actions. Recent research, however, has shown that low-dose of dietary CT could improve animal productive performance via enhancing antioxidant capacity and immunity and positively regulating gut microorganism composition and gut health without negative impact on feed intake and digestion. This article reviews the recent progress in the chemical structure, extraction and purification methods of CT and their applications in the ruminants, monogastric animals and aquatic animals, providing informative references for exploitation of CT as alternative to in-feed antibiotics in livestock, poultry and aquatic animals .