How can drench-resistant worms be kept out of your property?
Keeping drench-resistant worms out of your property is part of sustainable worm control.
Assume that purchased sheep are carrying worms with some degree of drench resistance to one or more drench groups.
1. ‘Quarantine’ drench all sheep (including rams) new to the property.
Use a combination of no less than 4 unrelated drench actives with at least one of these being the newest drench actives: monepantel (Zolvix®) or derquantel (with abamectin—Startect®). This can be done using multi-active (combination) and/or single-active products concurrently—up the race with one product, then up the race again with the next.
Do not mix different drenches unless the label states you can, as different products may be incompatible.
2. Quarantine the sheep after treatment.
Hold the sheep in quarantine in yards (small mobs) or a secure paddock (larger mobs) for at least 3 days to allow worm eggs present at the time of drenching to pass out of the gut.
Provide adequate feed and water.
Keep this paddock free of sheep, goats or alpacas for at least 3 months in summer or 6 months in cooler months.
3. After quarantine, release the sheep onto a paddock that is likely to be contaminated with worm larvae due to grazing by other sheep. This will ‘dilute’ (lower the proportion of) resistant worms surviving treatment with worm larvae already on your property.
4. WormTest the imported sheep 10–14 days after drenching for added confidence that treatment was successful.
5. Get expert advice on up-to-date recommendations for quarantine treatments. These will evolve as the drench resistance picture changes.