Sheep farmers are being encouraged to include the newer group four and five wormer groups into their parasite control plans to maximise lamb growth potential and to protect other wormer classes.
The advice comes from the Sustainable Control of Parasites in Sheep (SCOPS) group in an open letter, with the backing and support of the Moredun Research Institute, National Sheep Association, and the Sheep Veterinary Society.
They say for maximum benefit, these new groups should be used at two points in a worm control plan to keep lambs growing to their potential, and to maintain the older cheaper wormer groups as an effective option for as long as possible.
Although most sheep farmers will have heard of Zolvix, there are still some common questions around how it should be included in the flock worm control strategy:
1. Should we not be preserving the active in Zolvix for when we have no other treatment options left? Frequent use of the same active is one of the main drivers for worms to develop resistance. If we let the older three groups fail, we end up relying entirely on the newer groups. Over-use of these then makes their failure inevitable. By integrating Zolvix now, as part of the worm control strategy for the farm, will prolong the useful life of the older three groups, maintain effective levels of worm control, and not overuse the new actives.
2. In what situations should I be using Zolvix? It should be used on all sheep farms every year at two key points within a worm control plan - for all incoming sheep as part of their quarantine treatment and as a one-off annual break dose treatment for lambs in the latter part of the grazing season.
3. What is a break dose? A break dose is when the product is used in lambs in the latter part of the grazing season to remove the resistant worms left behind by previous treatments.
4. Once I’ve used Zolvix for the break dose in lambs, does that take care of their worm control for the rest of the season? No, it doesn’t. Zolvix is not a long-acting product. It is intended to clear the system quickly so as not to have any residual effect on the worm population. This helps to minimise the selection pressure for resistance. Further worming treatments, with other wormer groups, may be necessary depending on pasture contamination levels and weather conditions.
5. I currently rotate group 1, 2 and 3 wormers and do not think I have a resistance problem, should I still use Zolvix in my lambs? Chances are you do already have resistant worms on the farm, you just won’t see the problem unless you are testing regularly. But even if testing confirms there are no resistant worms present, including Zolvix in your worming plans now will reduce the risk of resistance developing to the three older wormer groups.