Sainfoin reduces the establishment of nematode infections in grazing lambs

Summary

Background: Recent studies with sheep have indicated an anti-nematodal effect of several leguminous plants, possibly associated with a high content of condensed tannins. In search for suitable local plants, an experiment was performed under Danish conditions.
Method: Four 0.3 ha plots were established with pure stands of sulla (Hedysarum coronarium), white clover, sainfoin (Onybrychus viciifolia) and chicory (Cichorium intybus). Five or six parasite naive lambs were grazed for 7 weeks on each plot with repeated moves to avoid reinfection. Lambs were infected 6 times during the first 3 weeks with Ostertagia circumcincta and Trichostrongylus vitrinus, receiving a total of 42,000 L3 of each species.
Results: The lambs grew at similar rates on white clover, sulla and sainfoin whereas the growth rate was considerably less on the chicory. Faecal egg counts (FECs) on sainfoin and sulla were consistently lower than on white clover and chicory. After 7 weeks of grazing, mean FECs were 1970, 1390, 980 and 900 epg in the white clover, chicory, sainfoin and sulla fed groups, respectively (p<0.01). The worm burdens were 24,800, 20,100, 15,900 and 18,700 (p=0.15) in the abomasum and 28,600, 21,100, 21,700 and 21,400 (p<0.02) in the small intestine in the white clover, chicory, sainfoin and sulla fed groups.
Conclusions: The establishment of nematode infections in sheep was influenced by the species of legume in the diet. Using white clover as a reference, sainfoin had the capacity to reduce infections almost similar to that reported for sulla. The reduction in faecal egg counts was larger (50%) than the reduction in worm burdens (24-36%).