Use of Clonostachys rosea against sheep nematodes developing in pastures

The fungus Clonostachys rosea f. rosea has the potential to control gastrointestinal nematodes (GIN) of sheep. A study was conducted using adult Merino sheep. Gender, egg count and initial body weights (BWs) were used to categorise animals into four groups which were randomly assigned to one of four C. rosea dietary treatments. Treatments were mixed with a complete diet and fed to sheep once daily for 10 weeks. There was no effect of treatment on eggs per gram of faeces. However, treatments reduced the number of larvae per gram in faecal cultures (P < 0.001) and larval development (LD) time (P < 0.001). Efficacy of treatments increased (P < 0.001) with time. On Day 70, treatments of 0.25, 0.5 and 1.0 g of C. rosea chlamydospores per kilogram BW reduced LD time by 33, 72 and 89%, respectively, whereas in the control, LD was reduced by only 2.6%. C. rosea significantly (P < 0.001) reduced numbers of third-stage larvae (L₃) found in pastures. Our findings suggest that daily feeding with C. rosea has a potential to reduce larval stages of GIN in pastures.