Journal article

A multi-species model to assess the effect of refugia on worm control and anthelmintic resistance in sheep grazing systems

RJ Dobson, EH Barnes, KL Tyrrell, BC Hosking, JWA Larsen, RB Besier, S Love, PF Rolfe, JN Bailey



OBJECTIVE: Develop a computer simulation model that uses daily meteorological data and farm management practices to predict populations of Trichostrongylus colubriformis, Haemonchus contortus and Teladorsagia (Ostertagia) circumcincta and the evolution of anthelmintic resistance within a sheep flock. Use the model to explore if increased refugia, provided by leaving some adult sheep untreated, would delay development of anthelmintic resistance without compromising nematode control. PROCEDURES: Compare model predictions with field observations from a breeding flock in Armidale, NSW. Simulate the impact of leaving 1-10% of adult sheep untreated in diverse sheep-grazing systems. RESULTS: Predic..

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University of Melbourne Researchers


Funding Acknowledgements

We are grateful for the assistance of the staff at CSIRO Chiswick field station for managing the field study. The late Ian Barger was instrumental in the development of the Haemonchus model and generously provided guidance, data and mathematical insights. Funding for the model development and field study was provided by Australian wool producers and the Australian Government through Australian Wool Innovation Limited and CSIRO. Financial assistance for conducting the simulation application study was provided by Novartis Animal Health Inc., Basel, Switzerland. Arthur Redpath and Andrew Little are thanked for their comments on draft versions of this manuscript.