Sheep and Goat Science Commons^™

Farmers' Estimations Of Sheep Weights To Calculate Drench Dose, R B. Besier, Diane Hopkins

Journal of the Department of Agriculture, Western Australia, Series 4

Undersosing with drenches is a mojor cause of anthelmintic (drench) resistance in worm parasites of sheep.

When farmers use a drench at less than the recommended dose rate, some worms may survive, and their ability to resist treatment with the chemical involved is passed to their offspring. Over a period of time, matings between worms with different degrees of resistance can produce individuals able to resist the drench at the recommended dose rate or even higher.

Farmers must use adequate dose rates so that worms do not have a chance to survive treatment.

Evaluation Of The Crack Approach For The Control Of Drench Resistance In Sheep Worms, J R. Edwards, Helen Chapman, Jon Dunsmore

Journal of the Department of Agriculture, Western Australia, Series 4

The Department of Agriculture launched the CRACK approach to worm control in September 1985 in response to finding that anthelmintic (drench) resistant worms were present on 68 per cent of a random selection of Western Australian sheep farms.

The high cost of internal parasites in terms of lost production and drench costs, together with the high prevalence of resistant worms of farms, confirmed that changes were needed to existing parasite control measures in sheep.l