Efficacy of Duddingtonia flagrans spores fed in trace mineral mix to lambs in reducing the development of gastrointestinal nematodes larvae in feces

Authors: Burke, Joan; Rohila, Suman; PRESTON, ELISA - Louisiana State University; WILLIAMS, CATHLEEN - Louisiana State University; SCULLY, CLARE - Louisiana State University; DELCAMBRE, BROOKE - Louisiana State University; PETERSSON, KATHERINE - University Of Rhode Island; KASS, ELIZABETH - University Of Rhode Island; ACHARYA, MOHAN - Lincoln University; MILLER, JAMES - Louisiana State University; VATTA, ADRIANO - Louisiana State University

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2025
Publication Date: 2/6/2025
Citation: Burke, J.M., Rohila, S., Preston, E., Williams, C.C., Scully, C.M., Delcambre, B.A., Petersson, K.H., Kass, E., Acharya, M., Miller, J.E., Vatta, A.F. 2025. Efficacy of Duddingtonia flagrans spores fed in trace mineral mix to lambs in reducing the development of gastrointestinal nematodes larvae in feces. Veterinary Parasitology. https://doi.org/10.1016/j.vetpar.2025.110414.
DOI: https://doi.org/10.1016/j.vetpar.2025.110414

Interpretive Summary: Gastrointestinal nematodes are one of the greatest health challenges to sheep and goats due to ineffective dewormers and production losses and possible death associated with nematode parasite infection. Alternatives to dewormers are essential to minimize parasite infection, but must be effective and easy to administer. A nematode-trapping fungus, commercially available, can control nematode parasites on pasture by consuming developing larvae before they reinfect animals; the product is placed on feed supplement. To test the application of including the fungus in a mineral mix, scientists from USDA, ARS, Louisiana State University, and Rhode Island University conducted studies comparing the recommended mixing with feed to including in mineral and found that both were acceptable in reducing larval recovery in the laboratory. This is important for grass-fed and range producers in need of parasite control in the environment; this study will greatly impact farmers, extension specialists, veterinarians, the feed industry and scientists with an aim of maintaining healthy livestock.

Technical Abstract: Providing spores of the nematode-trapping fungus, Duddingtonia flagrans, in the diet of livestock leads to fewer gastrointestinal nematode (GIN) larvae on pasture. The objective was to determine the viability of D. flagrans (Df; BioWorma®) fed in a mineral mix compared with a feed supplement to naturally infected lambs (predominantly Haemonchus contortus and Trichostrongylus/Teladorsagia spp.) to reduce the number of GIN larvae cultured. Initially, the viability of Df spores was examined in a preliminary experiment in which lambs were fed a control supplement without Df (CON) or with Df (n = 8/treatment) for 7 days. Feces were collected every other day for three coprocultures. Feeding Df led to a 73% reduction in stongylid third-stage larvae (P = 0.005). In the second experiment, weaned lambs were fed a 12% crude protein grain supplement with trace mineral added without Df (CON), Df mixed in feed (DfC) or in trace mineral (DfM; n = 8/treatment) for 16 days. Strongylid larval recovery was reduced in both Df groups (P < 0.001), and the third-stage larval recovery was lower in DfM than DfC (P = 0.001). In a field study, similar treatments were used (n = 16/treatment including 2 reps/treatment) using weaned lambs for a 30-day period. The sheep were fed a 16% crude protein commercial grain mix and a commercial mineral mix; for the DfM group, Df spores were mixed with the mineral mix 7 days prior to feeding. Similarly, strongylid larval recovery was reduced in both Df groups (P < 0.001) but was similar between Df treatments (P = 0.62). No treatment effect on Strongyloides larvae recovered was noted (P = 0.181). Including Df in a trace mineral mix offers promise in control of GIN on pasture or range for flocks that do not offer grain supplements.