For the first time in 22 years producers have a new drench to control worms in sheep and Industry & Investment (I&I) NSW has advised prudent use to maintain its effectiveness.

State co-ordinator for internal parasites, I&I NSW veterinarian, Stephen Love said monepantel represents a new drench group known as amino-acetonitrile derivatives or AADs.

“Being new, it’s highly effective and will do a good job on worms in its own right, but AADs can also be used in rotation with older drenches to keep them viable,” Dr Love said.

“Current evidence suggests rotation with older drenches within a season has the edge on annual or longer rotations.

“Monepantel is great news for producers as long as it is used wisely to reduce the development of resistance.

“The consensus is that using a combination of unrelated broad-spectrum drenches will raise efficacy and delay resistance better than using just one drench for the whole season.

“Producers need to know precisely what drenches or drench combinations work on their property to develop a sensible system of drench rotations.”

Dr Love said producers could test the efficacy of drenches on their farms by using WormTest before and after drenching.
“Regular WormTests will help avoid unnecessary drenching which not only reduces the risk of developing resistance, it saves time and money,” he said.

“It’s important to use the correct dose, based on the weight of the heaviest animals in the mob and to use accurate equipment to measure and deliver the dose.

“And don’t import resistance – when new sheep are brought onto the property treat them with an effective combination of drenches and then hold them in a quarantine area for four days prior to moving them onto the farm.”