Parasites are a common problem with ruminants and other animals and tannins may offer a natural solution to battle parasite infections
Parasites affect the health and productivity of ruminants such as cows and sheep. For this reason commercial synthetic drugs need to be used every year to combat parasite infections. Unfortunately a global resistance against parasites is growing and alternative solutions to synthetic anthelmintic drugs are needed. This is important since resistance formation tends to increase the used drug doses and this may be reflected as increased environmental releases of the drug residues or the residues may end up into the final products such as milk, cheese and meat. Parasites also form a health problem to humans in developing countries. Therefore it would be important to know whether tannins of certain plant species could be used to efficiently lower the load of parasite infection in any organism suffering of them.
At the moment it is known that certain tannin-rich plant species are able to affect three different life stages of intestinal nematodes of ruminants: (1) the eggs, (2) the infected larvae, and (3) the adults. Depending on the plant species and its tannins the efficacies have varied from negligible to even 90%. Clear structure-activity patterns are currently constructed with the help of purified tannins to explain the activity and inactivity of the tested species.