December 2013
Is the fungus still among us? The answer is yes
By Jim Miller
Parasitologist
Louisiana State University
Livestock defecate on pasture, and feces include gastrointestinal (GI) nematodes eggs. For completion of the life cycle of GI nematodes, larvae that hatch from eggs have to develop and survive to the infective stage and then migrate out of the feces to be consumed by grazing animals. Duddingtonia flagrans is a nematode-trapping fungus that is able to eliminate the majority of those free-living larval stages in the feces.
This is accomplished by incorporating D. flagrans spores into a daily feed supplement. They are able to survive and pass through the GI tract and are deposited in the feces along with the nematode eggs.
The spores germinate and form sticky loops that trap larvae as they migrate through the feces. Once trapped, the fungus kills the larvae, thus, reducing the larval population on pasture that is responsible for reinfection.
The product is designed to be fed during periods of high pasture contamination. Spores fed (6-8 weeks) to peri-parturient dams can reduce contamination due to the peri-parturient rise in fecal egg count. Spores then fed (8-10 weeks) to offspring after weaning (beginning of “worm season”), will continue to reduce contamination.
This product does not affect the worms in the animal so deworming may still be necessary. Deworming should be administered only to individuals that need it based on FAMACHA©, fecal egg count, etc.
From the mid-1980s through the early 2000s, research and field testing of D. flagrans was undertaken in Europe and the US to provide the base for commercial production of a product to help clean up pasture contamination.
Unfortunately, the company that was developing and promoting the product terminated production. However, International Animal Health, an Australian company, continued to pursue studies in efforts to re-establish D. flagrans as a viable commercial product.
After years of refining the process, their new product has been tested under laboratory and field conditions. The results have shown excellent control in reducing GI nematode larvae in feces.
This product is not commercially available in the US, but the company is exploring that possibility.