The Anti-Nutritional Effects and the Degradations of Dietary Tannins: A Review
Tannins are a complex group of plant secondary compounds widely found in plant kingdom.Tannins mainly exist in various organs and tissues of plants. Tannins are conventionally classified into three groups: hydrolysable tannins, condensed tannins and complex tannins, according to the structures and properties. Tannins, as important anti-nutrients, exhibit detrimental effects to various animals by reducing voluntary feed intake, nutrient bioavailability and toxicity. The mechanisms of reducing nutrient bioavailability to animals were reported mainly as decreasing digestibility and absorption of nutrients, decreasing nitrogen balance in animals, changing microorganism diversity in the gastrointestinal tract, and producing toxicity to digestive systems. Treatments including physical-chemical and biological processes were reported to successfully avoid negative effects of tannins. Physical-chemical treatments mainly are soaking, drying, de-hulling, extruding, alkali treatment, polyethylene glycol (PEG) treatment and radiation. The biological treatment meanly includes solid-state fermentation. The anti-nutritional effects and methods of degradation of tannins are reviewed in this article.
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NSTL
万方数据
维普
