The Sustainable Control of Parasites in Sheep (SCOPS) has reported that use of the two newer wormer groups (4-AD orange and 5-SI purple) has doubled in the two years since they became available through SQPs at merchants, but sheep farmers could still harness their potential more.

That is the message from SCOPS, which has campaigned hard to encourage sheep farmers to carefully integrate the two newer groups into their worm control programmes.

Speaking on behalf of the group, Lesley Stubbings said: “It’s great news that we have more than doubled the number of doses of the newer wormer products used in the UK. This means many more flocks are harnessing the potential these products have to slow the development of resistance and improve late season lamb growth rates.

“It also means fears they would be used too widely when the classification changed were unfounded. We now need to push to get even more flocks adopting one of the groups as a one-off annual dose and part of their quarantine treatments.”

Integrating the two newer groups into on-farm worming strategies will help slow resistance to the older groups, Ms Stubbings said, keeping them working for longer.

As well as being an important option for quarantine treatment of incoming stock in the autumn, SCOPS recommends that either of the two newer wormers are used as a ‘mid-season’ or ‘break drench’ to remove worms that have survived prolonged exposure to other wormer groups used earlier in the season.

Ms Stubbings added: “To get the most out of this one-off annual drench it is important to use it in the latter part of the grazing season. The objective is to remove worms that have survived previous treatments with one or more of the older groups (1-BZ white, 2-LV yellow and 3-ML clear).

“This helps slow the development of resistance to these three groups, with the double benefit that killing the build-up of worms surviving in the lambs will boost performance.”