Evaluation of new formulations of nematophagous fungi Duddingtonia flagrans to control gastrointestinal nematodes in post-weaning lambs in Colombia Andean region.

Gastrointestinal nematodes (GIN) can reduce or limit sheep production. Nematophagous fungi are natural enemies of GIN and can be used as a biological control tool by reducing the use of anthelmintic drugs. This study, conducted in the Colombian Andean region (Mosquera, Cundinamarca) under tropical conditions, aimed to evaluate the effectiveness of novel granular formulations (E3, E16) based on Duddingtonia flagrans (native strain) against GIN in a controlled field trial. Four different groups of post-weaning lambs (n = 9) naturally infected with GIN were allocated in separate paddocks and received daily fungi formulations identified as E3, E16, and fungus dried biomass (DB) at a dosage of 1 × 106 chlamydospores/kg of body weight for 18 weeks, excepting control group. Parasitological criteria such as the number of eggs per gram of feces (EPG) and larvae pasture count (L3/ Kg DM) recovered were monitored. The estimated EPG reduction of the developed formulations was 62.7 %, 80.2 %, and 62.3 % for E3, E16, and DB, respectively. There was a significant reduction between the treated groups and the control group (p < 0.05). Regarding EPG, no significant differences arose between E3 and E16 formulations. The formulation E16 reduced pasture larvae count up to 89 %. The effect of formulations persisted for at least 42 days after the last fungus administration. Therefore, using these formulations would provide an alternative option to control GIN parasites on pasture and in animals. • Efficacy of Duddingtonia flagrans formulations against gastrointestinal nematodes. • Reduction of nematode count in feces (EPG) up to 80 % by formulation E16. • Solid coated formulation E16 reduced pasture larvae count up to 89 %. • The effect of formulations remains for 42 days after the last administration. [ABSTRACT FROM AUTHOR]