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Make The Most Of Your Sheep Wormers

6 September 2017

There has been a lot of talk about resistance to anthelmintics over the last 10-15 years so, if this is the case, why have we not seen more sheep farms being unable to farm sheep? This is because resistance doesn’t always mean the product will completely fail. Rather, it means there is a reduction in the percentage of worms killed by a particular wormer which increases over time. This affects productivity and often the effects can be hard to see unless you are monitoring growth rates or other production measures. Even low levels of resistance can leave enough worms behind to affect growth rates. Indeed, when the number of resistant worms is more than 10%, we start to gradually lose lamb performance because the product is not performing at its optimum level. This is why we need to act now and put a sustainable worm control programme in place.

Resistance to the three older wormer classes is increasingly common on many sheep farms. Research from Wales showed resistance to all three of these older wormer classes: 94% resistance to white wormers; 68% resistance to yellow wormers: 51% resistance to ivermectin and 19% resistance to moxidectin.

Using a post-drench efficacy test to test the effectiveness of the wormer used is important to understand the effectiveness of any wormer treatment given. Wormers are an investment in your flock so this is a way to making sure you are getting the most for your money by understanding what product you should be using. Integrating the newer generation wormer classes early, such as Zolvix® the 4-AD (monepantel) group, will ensure you are using an effective wormer because there is no reported resistance in the UK and it may also help to slow down resistance development, thereby prolonging the efficacy of the older classes.

As a mid-late season clear out dose in lambs Zolvix should be used

  • Zolvix clears out resistant worms that, having survived earlier treatments, may be limiting lamb performance.
  • Helps to improve health, live weight gain and productivity.
  • Reduces contamination of the pasture with resistant eggs.

Farm Protection (Quarantine Dose)

  • All sheep arriving onto a farm, however healthy looking, can bring resistant worms.
  • Dose all incoming sheep with Zolvix to help protect your farm from resistant worms

Remember anthelmintic resistance, once it has developed, cannot be reversed. Act now and incorporate the new wormer classes to help preserve all wormer classes for flock health and welfare.

For more information visit or talk to your vet or animal health adviser. Zolvix will be available to purchase direct from Suitably Qualified Persons (SQPs) from July 2017.

Kirsty Brown


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