[Effects of tannins in animal nutrition].

Tannins are watersoluble plant polyphenols that precipitate proteins. According to their chemical structure they can be divided into condensed tannins and hydrolysable tannins. Altogether, tannins are reported to have various physiological effects like anti-irritant, antisecretolytic, antiphlogistic, antimicrobial and antiparasitic effects. Phytotherapeutically tannin-containing plants are used to treat nonspecific diarrhoea, inflammations of mouth and throat and slightly injured skins. Studies with ruminants have also demonstrated that the denaturing properties of tannins can possibly be used to improve protein supply to the small intestine. Besides anthelmintic effects of condensed tannins have been observed in sheep and goats. On the other hand high tannin concentrations resulted in reduced animal performances and health disorders as well in ruminants as in monogastriers. Further scientific research is therefore needed to clarify whether tannins can be effectivly used in livestock feeding, for example in prophylaxis of diarrhoea or parasitic control.