The Department of Agriculture and Food is encouraging sheep producers to test drench resistance in their lambs.
Department principal veterinary officer Brown Besier said ineffective drenches had a major impact on sheep health and production over the course of a year, even though the consequences weren’t immediately obvious.
“It’s important to test resistance for all available drenches because test results show that some widely-used drenches, such as abamectin and moxidectin, are no longer always fully effective,” Dr Besier said.
“For best results, lambs up to about six months of age that have not been drenched in the previous two months should be tested at the time when they’re most susceptible to worms – from weaning to summer drenching time.
“Drench resistance testing involves sheep owners drenching and sampling sheep, with laboratory testing conducted by private veterinarians or the department’s Albany laboratory.”
The department has developed a sheep worm drench resistance kit that includes everything required and tests for resistance to four commonly-used drenches: abamectin, moxidectin, a white-clear drench combination, and a white-clear and abamectin combination.
It also contains quantities of the four drench types as well as sample containers, pre-addressed postage bags and clear instructions.
The $440 kit cost covers laboratory costs for 60 worm egg counts and the identification of worm types in the test groups and an undrenched control group.
Dr Besier said laboratory testing was conducted by the department. Results were based on the reduction in worm egg counts in small groups of sheep after treatment with different types of drenches.
“Lab test results include a detailed report advising how well the drenches worked against specific worm types and recommendations on good worm control to minimise drench resistance,” he said.
“Producers are forwarded their test results within two weeks and are advised to discuss the results with a veterinarian to help plan their sheep management program.”
Kits can be obtained by phoning department offices in Albany, Esperance, Katanning, Narrogin, Merredin, Moora and Manjimup.