Interaction Between <em>Duddingtonia flagrans</em> and <em>Pochonia chlamydosporia</em> for the Biological of Bovine Gastrointestinal Nematodes

Gastrointestinal nematodes are among the most significant parasites affecting liverstock health and productivity, leading to major economic losses and contributing to the global increase in resistance to anthelmintics. Biological control using fungi with ovicidal and nematophagous activity offers an environmentally friendly alternative. This study investigated, for the first time, the interactive effects between the nematophagous/larvicidal fungus Duddingtonia flagrans and the ovicidal fungus Pochonia chlamydosporia under natural infection conditions. Eighteen Holstein × Zebu males (12–15 months old) were divided into three groups (n = 6): T1 (D. flagrans), T2 (D. flagrans + P. chlamydosporia), and control. Treatments were administered orally daily (6 g/100 kg BW of each fungus; 10⁶ chlamydospores/g) for nine months. Faecal egg counts (EPG) and infective larvae in pasture (L3) were monitored. Groups T1 and T2 showed significantly lower EPG values than the control during most of the experimental period. Haemonchus spp. was identified as the predominant nematode, confirming its epidemiological relevance. The combined fungal treatment exhibited synergistic activity, enhancing parasite suppression through complementary ovicidal and larvicidal mechanisms. This approach proposes a sustainable and reproducible alternative to the excessive use of chemical compounds, contributing innovative and applicable solutions to national livestock production and integrated animal health.