Group 4 and 5 products

For many years UK sheep farmers were reliant on only three groups of wormers – 1-BZ (white), 2-LV (yellow) and 3-ML (clear). The addition of two new groups – 4-AD (orange) and 5-SI (purple) – is great news for efforts to slow anthelmintic resistance, as long as they are used and used correctly. 

SCOPS encourages the integration of the two newer groups into on-farm worming strategies to help slow resistance to the older groups, keeping them working for longer. In the long term this means cheaper, effective worm control compared with the dangerous prospect of having to rely on the newer groups completely. Not only would that be very expensive, but if the newer groups become the only treatment option then resistance to those would increase rapidly. The two newer group are most effectively used as a late season break dose and a quarantine treatment.

Late season break dose

The objective of a late season break dose is to remove worms that have survived previous treatments with one or more of the older groups. 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. Follow these break dose top tips to maximise this option:-

• Don’t assume a break dose should be given at weaning time. Leaving it until later in the summer, when there is a greater build-up of worms, will likely reap the biggest benefits.
• Drench all remaining lambs, to maximise the chance of killing all resistant worms. This is different to the normal SCOPS advice, which is to leave the biggest or fittest lambs untreated when using the older groups of wormers.
• Do not dose-and-move, as this will encourage development of resistance to the group 4/5 product used. Drench the lambs, return them to the same fields and then move them after four or five days. This makes sure they will pick up a few untreated worms to take with them. Find our more about alternatives to drench-and-move at www.scops.org.uk/internal-parasites/worms/preserving-susceptible-worms. 

Quarantine

The gold, silver and bronze quarantine recommendations all include using a 4-AD (orange) and/or 5-SI (purple) product. This is because there is little/no reported resistance to either of these products in the UK to date, so they have the most chance of killing any resistant worms inside sheep arriving to your farm. Once treated, sheep must be turned out onto dirty pasture, so any resistant worms that survive are diluted by susceptible worms already on the farm. Follow the link above to find out more on preserving susceptible worms. Find the full SCOPS quarantine recommendations at www.scops.org.uk/internal-parasites/quarantine-advice-for-internal-and-external-parasites. And watch this AHDB 'Effective quarantine when worming sheep' video.

Extra information

• Only the late season dose and quarantine treatments are the recommended times to use the newer products. Never use them in ewes or at other times without detailed advice from your vet.
• At a global level, where resistance to the 4-AD (orange) product has been confirmed it has been on farms relying either heavily or entirely on this product. This highlights the need for UK sheep farmer to follow best practice advice and reveals the dangers of not integrating the newer wormer groups into on-farm control programmes before the other groups fail. Click here to read more about confirmed cases.
• If you have reason to believe you have multiple anthelmintic resistance (MAR) on your farm, it is very important not to immediately start relying solely on the group 4 and 5 products. Explore your options at www.scops.org.uk/internal-parasites/worms/testing-for-efficacy/interpreting-results