Master of Science (MS)


Veterinary Medical Sciences - Pathobiological Sciences

Document Type



Gastroenteritis caused by the nematode parasite Haemonchus contortus is a serious concern for small ruminants in the tropics and subtropics. Control is traditionally by anthelmintics and pasture management, however this specific nematode parasite has become resistant to many anthelmintics and research is now focused on novel control methods including biological control using the nematode-trapping fungus, Duddingtonia flagrans. The objective of this study was to investigate the effectiveness of feeding chlamydospores of the fungus at a dosage of 5 x 105 spores/kg of BW to ewe/lamb pairs (Trial 1) and weaned lambs (Trial 2) for a total of 17 and 8 weeks, respectively. For Trial 1, 34 pregnant ewes were randomly allocated into Treated and Control groups of 17 each and each group grazed on separate pastures for 21 weeks. For Trial 2, 30 lambs from Trial 1 were randomly allocated into Treated and Control groups of 15 each and each group grazed the same pastures as in Trial 1. In both Trials, results from fecal cultures, pasture larval recovery and tracer animals showed that the Treated group pasture had lower infectivity. This reduced pasture infectivity did not translate into reduced infection levels in the ewe/lamb pairs in Trial 1, but infection levels were reduced in Trial 2. There was no effect on weight gain in either Trial. It can be concluded from this study that Duddingtonia flagrans can be used as a biological control agent to reduce pasture infectivity, however, infection levels and productivity may not be affected in sheep during one grazing season.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

James E. Miller