When you bring livestock onto your farm, they can bring along their entourage of undesirables and there is only one opportunity to keep these unwanted organisms away.
The awareness of the presence of triple combination resistant worms (those that can survive a full dose of a triple combination ML-BZ-Lev oral drench) in New Zealand should be high. Unfortunately, there is no quick and easy test to determine if the stock you are purchasing have these triple resistant worms in their gut, so it is best to assume that they do.
To prevent the introduction of triple drench resistant parasitic worms onto your farm, use a novel anthelmintic such as Zolvix Plus in both sheep and cattle. After drenching, put the animals in a paddock that has a worm burden so that any resistant eggs can be diluted by drench susceptible ones.