Triple Drench Resistance: Not Just a North Island Problem

Triple Drench Resistance: Not Just a North Island Problem

Drench resistance is happening in the South. Vet Donna looks at how it can be managed.

Every year we run some Faecal Egg Count Reduction Tests (FECRT) on our farms to see how well the drenches are performing.

In the past, we have found that in many cases there is some level of resistance to the single active drenches. However, over the past few years, we have been finding more and more drench resistance to the drenches in double and now triple combinations in our patch – Otago and Southland!

This has come as a surprise to some farmers, and other farmers have kind of expected it. When we find these issues there are lots of things we can do to help manage their stock and continue to produce in spite of drench resistance. However, if it is not identified, and not dealt with, it will continue to get worse and production will suffer.

Drench is only one part of a large puzzle to parasite management. But we rely on it heavily to achieve high levels of production from our stock. It is important to find a balance between production and sustainability. Farmers need to address other parasite management factors in order to manage this balance. A Beef and Lamb Wormwise workshop is a great way to get skilled up on these.

You can find an excellent podcast produced by Beef and Lamb NZ, where three farmers are interviewed about their experience with triple drench resistance. I encourage you all to listen to it and hear their stories.

What exactly is Drench Resistance?

Drench resistance is defined as a drench that is killing less than 95% of the parasites present. We calculate this by measuring the Faecal Egg Counts of lambs, then drenching them with specific drenches (single actives and combinations) based on their weights. Two weeks later we take faecal samples from these animals for Faecal Egg Counts to calculate the reduction. We also use Larval Culture (hatching the eggs and counting the larvae) to assess what parasites are causing the problems.

We can organise this testing for your animals, just contact your KeyVet to book it in.

- Donna Hamilton


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