Prevention of clinical trichostrongylidosis in calves by strategic feeding with the predacious fungus Duddingtonia flagrans.

The present investigation showed that strategic feeding of first-season calves with the microfungus Duddingtonia flagrans through the initial 3 months of the grazing season could prevent severe clinical trichostrongylidosis in the late summer. The successful prevention of disease was particularly noteworthy in view of the high stocking rate practiced on this permanent pasture, which was widely contaminated with a range of gastrointestinal nematodes. The results showed that larval populations of Ostertagia and Cooperia were significantly reduced on the pasture grazed by the fungus-treated calves. Numbers of Nematodirus seemed less affected. The present paper discusses the complexity of fungus-nematode interactions in dung pats under natural conditions.