parasite control supplement

Could adding a supplement to your horses’ feed reduce the worm burden on your pasture? Researchers recently tested an Australian product designed to do just that—and with positive results.

In recent field trials a feed supplement (commercially available in Australia as BioWorma) effectively reduced the “gastrointestinal nematode (GIN) infectivity of pasture surrounding the feces of treated horses,” the researchers said.

The supplement contains spores of the fungus Duddingtonia flagrans IAH 1297. The fungal spores pass through the horse’s gastrointestinal tract unharmed and are deposited in manure. There, they germinate and grow a mass of fungal hyphae—fine rootlike structures—and sticky traps that inhibit worm larvae, ultimately trapping and killing them.

Kevin Healey, MAppSc, MSc, lead author of the study and research and development manager of International Animal Health Products (IAHP) Pty Ltd, Australia, said the study results suggest D. flagrans could lower the incidence of parasite infection of animals grazing the pasture.

The horses the team studied had naturally acquired parasite infections, consisting principally of cyathostomes, plus some Strongylus spp. and Trichostrongylus axei. After eight weeks of supplement administration, the researchers found that the overall average number of worm larvae in the feces was reduced by 84%.

Healey and fellow study author Chris Lawlor declared an interest in the research through their links to IAHP. The study’s other authors—Dr. Malcolm R. Knox, of the Commonwealth Scientific and Industrial Research Organisation Livestock Industries F.D. McMaster Laboratory, in New South Wales, Australia; Michael Chambers, BVSc Hons, MVSt, MANZCVSc, GCAS, director of research services, and Jane Lamb, BS, a PhD student, from Invetus, in New South Wales; and Peter Groves, BVSc (Hons), MACVSc (Epidemiology), PhD, of Zootechny, in New South Wales—had no such links and were responsible for conducting the field trials.

Healey said the study showed that administering the supplement to horses and other livestock, including cattle and goats, could “lead to decreased levels of GIN infection in animals grazing pasture where this product is used and would provide an alternative means of controlling parasitic nematodes. Importantly, BioWorma is equally effective against worms that have developed resistance to chemical wormers.”

The study, “Field evaluation of Duddingtonia flagrans IAH 1297 for the reduction of worm burden in grazing animals: Pasture larval studies in horses, cattle and goats,” was published in Veterinary Parasitology.