Use of Tannins in Livestock Nutrition

Abstract

This study aimed to evaluate the effects of tannins and tannin-containing plants at different inclusion levels in animal diets by reviewing various feeding studies involving different livestock species. Tannins are phenolic compounds produced by plants, particularly woody species, as a defense mechanism against external factors. They are classified into two major groups: hydrolysable tannins and condensed tannins. Tannins are known for their ability to bind proteins, inhibit microbial enzymes, and exert antibacterial effects by disrupting bacterial membranes. In ruminants, condensed tannins form complexes with proteins within the pH range of 3.5–7.5, thereby reducing microbial degradation in the rumen and improving bypass protein availability. Positive effects such as increased growth hormone levels, inhibition of gastrointestinal parasite larvae, and improved nitrogen utilization have been observed, especially in ruminants. However, high tannin levels (above 60 g/kg DM) may reduce feed palatability and intake due to their astringent taste. Safe inclusion levels have been reported as 8–10% in goats, 3–5% in cattle, and approximately 1% in poultry. In conclusion, tannins can be used strategically in livestock nutrition to improve health and performance parameters when administered at species-appropriate and controlled levels.