Bringing alternative control methods into parasite management guidance

In his undergraduate dissertation research, recent RAU graduate Henry Holder explored the case for integrating holistic and historical control methods alongside conventional chemical treatments, both in day-to-day farm practice and in the frameworks that guide it. He highlighted alternative control options which can act as additional tools and, when used well, can reduce reliance on chemical treatment.

Biological parasite control using Duddingtonia flagrans

One of the most established alternatives to anthelmintic treatment is using the nematophagous fungus Duddingtonia flagrans. A form of biological control, this naturally occurring fungus can trap and destroy nematode larvae within dung on pasture, reducing the infective larval challenge before grazing animals ever encounter it.

Through his review of existing academic research on the topic, Henry highlighted that D. flagrans is the standout candidate among nematophagous fungi because its chlamydospores survive passage through the ruminant gut and go on to form larvae-trapping networks in the faeces. Trials have shown it can reduce infective Haemonchus contortus larvae in faeces by between 82.8% and 99.7% — a striking figure when standard anthelmintics are expected to achieve at least 90% efficacy.

Reviewing options for alternative parasite management

Alongside fungal biocontrol, Henry’s dissertation looked at tannin-rich forages, cross species grazing systems, host genetic variation (breeding for parasite resilience or resistance), vaccination — including the Barbervax vaccine against Barber's Pole worm — and developments in diagnostics.

Henry highlighted that not every measure suits every landscape. In the Cotswolds, where farms are typically ring-fenced with limited pasture-sharing between units, a cross-species grazing system would be far more practical than it would be on common land such as the New Forest, where stock from multiple owners already graze together.

Getting these right matters because both the parasite challenge and the practicality of any given solution genuinely differ from place to place. Introducing regionally appropriate alternative measures could reduce parasite burden directly and reduce chemical treatment reliance as a natural consequence — both because burdens fall and because best practice becomes easier to follow.

None of the options are proposed as replacements for conventional anthelmintics, but they are additional tools that can reduce reliance on chemical treatment and help slow the development of anthelmintic resistance.

Innovation for Agriculture thanks Henry Holder for his input into this article and sharing insights from his undergraduate research dissertation to enable others to benefit from them.