Responses in the physiology of ruminal digestion to the use of tannins in ruminant feeding

Abstract

The livestock activity in Brazil is basically represented by the pastoral system. However, climatic adversities promote a lack of uniformity in forage supply and quality, leading to greater intensification of production systems. The search for feeding alternatives aiming to improve animal performance has been the object of many researches, such as the use of forages adapted to certain environmental conditions. Generally, these plants may have compounds that alter animal production, either positively or negatively. These compounds include condensed tannins (CT), which are polyphenolic compounds from secondary plant metabolism. At high concentrations (6 to 12% of dry matter (DM)) they reduce palatability, consumption, enzyme activity, protein and carbohydrate digestibility, and consequently reduce animal performance. However, when this consumption is medium or low (2 to 5 % of DM), it allows an efficient use of dietary protein, forming complexes through hydrogen bonds, thus protecting the protein from ruminal degradation, increasing amino acid flow for intestinal absorption. In addition to improving the protein efficiency of the diet, CT can be said to reduce methane production, and bring benefits in the control of gastrointestinal parasites, improves reproductive performance, fetal development, immune system response, serum hormone concentrations, wool production and lactation. The use of plants with low concentration of condensed tannins may be a good nutritional strategy for ruminants, provided that its mechanism of action on protein metabolism is considered. This review aims to provide some answers to the use of CT in ruminant feeding, focusing on changes in rumen digestive physiology, which becomes responsible for the secondary consequences of tannins on animal production.