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Duddingtonia flagrans is a biological alternative to the use of anthelmintic drugs in ruminants. This fungus must be ingested by the animal, pass through the cavities of the digestive tract and reach the feces where it develops traps that capture the nematodes. The severe conditions encountered in this process negatively affect the fungus, which is reflected in the low recovery rates compared to the amount administered. The aim of this study was to evaluate independently the in vitro effect of typical physical and chemical conditions of the gastrointestinal cavities of ruminants on the concentration, viability, and the in vitro nematode predatory ability of the chlamydospores of D. flagrans. The factors evaluated individually were pH (2, 6, and 8), temperature (28 ± 2°C and 39 ± 2°C), exposure to artificial saliva, and milling. The results showed that the concentration and viability of D. flagrans were not affected by the action of pH, temperature, milling, or exposure to artificial saliva. Regarding the in vitro nematode predatory ability, a reduction was observed after the milling process and the exposure for 24 h at different pH., (© 2021 Wiley-VCH GmbH.)

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]