Tannins for suppression of internal parasites

ABSTRACT: It is increasingly evident that gastroin-testinal parasite (GIP) control programs based on de-wormers are failing because of increased dewormer re-sistance; thus, alternative GIP control strategies are necessary. Condensed tannins (CT) have biological ef-fects that may aid in the control of GIP. The CT bind proteins and other molecules tightly at near-neutral pH, such as occurs in the rumen, with dissociation in the acidic pH of the abomasum, freeing them for digestion. Plant CT may have direct or indirect effects on GIP. Direct effects might be mediated through CT-nematode interactions, thereby affecting physiological function-ing of GIP. Condensed tannins extracted from various forages can markedly decrease the viability of the larval stages of several nematodes in sheep and goats. Con-