RESUMO
Horses can harbor a large amount of parasites that may cause serious clinical signs even death. The aim of this study was to evaluate the predatory activity of the fungus Duddingtonia flagrans against infective larvae (L3) of gastrointestinal nematodes of horses in fecal culture. The experimental design was completely randomized with three treated groups (G1, G2 and G3) and one control (CG), using eight animals/group. The treated animals received G1: 1.5 × 10(5); G2: 3 × 10(5) and G3: 6 × 10(5) chlamydospores of D. flagrans/kg body weight during 21 days. The fungi preparation was given at every other three-day interval. Faecal samples were collected during 30 days, on the same interval, to perform the fecal egg counts (EPG) and fecal culture for each horse. All groups demonstrated similar results for the EPG (P > 0.05) counts. D. flagrans significantly reduced (P < 0.05) the number of infective larvae after 72 h-interval between treatments. The G2 and G3 promoted higher results (P < 0.05) of L3 reduction compared to the CG. The biological control with the predacious fungi D. flagrans is still a promising free-living parasite regulator alternative to be use in livestock.