Effects of condensed tannins on goats experimentally infected with Haemonchus contortus

Nematode control in ‘green’ ruminant production systems

Collectively, nematode parasites of domestic ruminants continue to pose the greatest disease problem in grazing livestock systems worldwide, despite the powerful and extensive chemotherapeutic arsenal available for their control. The widespread development of anthelmintic resistance, particularly in nematode parasites of small ruminants, and the trend towards non-chemical (ecological, organic, green) farming of livestock has provided an impetus for the research and development of alternative parasite control methods. This article provides a brief overview of the non-chemotherapeutic options for parasite control and how they might play a role either in organic farming or in other low-input farming systems.

In vitroeffects of three woody plant and sainfoin extracts on 3rd-stage larvae and adult worms of three gastrointestinal nematodes

Most studies on the effects of tanniferous plants on nematodes have examined forages but have neglected the woody plants. Therefore,in vitroeffects of extracts from 3 woody plants (Rubus fructicosus,Quercus robur,Corylus avellana) have been tested on trichostrongyles and compared to sainfoin, a legume forage. Because somein vivoresults indicated that the effects of tannins differed depending on the parasitic species and/or stages, the effects were measured on 3rd-stage larvae (L3) and adult worms ofTeladorsagia circumcincta,Haemonchus contortusandTrichostrongylus colubriformis. The effects of plant extracts varied according to the plant sources, the parasite species and stages. For the woody plants, significant inhibitory effects were obtained on both stages of abomasal species. Results forT. colubriformiswere more variable. Effects of sainfoin extracts were significant onT. colubriformisandH. contortusL3, and on abomasal adult worms. In order to assess the implications of tannins, polyethylene glycol (PEG), an inhibitor of tannins, was added to hazel tree, oak and sainfoin extracts. Without PEG, significant inhibitory effects on L3 and adult worms were confirmed. After addition of PEG, the larval migration and motility of adult worms were restored in most cases. These results confirm variations in effects depending on factors related to plants or parasites and suggest that tannins are partly responsible for the effects.