Sheep farmers who have not yet dosed lambs this season with a newer group 4-AD (orange) wormer are being urged to do so now, following a major peak in worm egg counts.
Data from a worm egg surveillance programme across over 70 UK sheep farms has shown a significant increase in worm egg counts this autumn. This surge comes following a dry summer, which meant worm burdens remained relatively low.
Matt Colston, vet at Elanco Animal Health, says it is vital that farmers worming lambs this autumn use a group 4-AD wormer, such as Zolvix™, if they have not already done so.
“Farmers mustn’t rely solely on the older group 1, 2, and 3 wormers,” warns Mr Colston.
“Wormer resistance is a huge problem, albeit usually invisible, with research showing that 94% of farms are resistant to white wormers, 68% resistant to yellow wormers, 51% resistant to ivermectin and 19% resistant to moxidectin[1].
“Continuing to use only older actives is likely to result in worms being left behind after treatment which can reduce growth rates in lambs by up to 50%, before any visible signs are present[2],” explains Mr Colston.
He adds that repeated use of the same wormer groups will also contribute to a growing level of resistance, with a potentially devastating impact for worm control in future years[3].
“Wormer resistance is a problem that is already increasing under the radar on most farms. Once established on a farm, a resistant worm population cannot be reversed,” he says. “Regardless of the current level of resistance on individual farms, it’s crucial to strategically introduce a newer group active into wormer regimes now. Beyond the cost benefit of an improvement in lamb performance, due to worms being effectively cleared out, the introduction of Zolvix now will help to slow the rate of resistance build up to the older group wormers.
“This will allow the group 1,2 and 3’s – which still play a vital role in worming strategies – to be used for much longer,” he continues.
Advice from SCOPS recommends that all sheep farmers use either an orange (4-AD, Zolvix) or purple (5-SI) wormer at two key points in the year: As a one-off mid to late season dose for lambs, and for all incoming stock as part of a quarantine treatment.
“After a quarantine dose, sheep should be housed or yarded for 24 hours before moving to ‘dirty’ pasture. However, after treating lambs with a break dose, keep them on ‘dirty’ pasture for three to four days before moving,” says Mr Colston.
“Other SCOPS principles must also be followed. This includes testing before treating to ensure there is a need to treat, and accurate dosing,” he concludes.
Sheep farmers are encouraged to utilise Elanco Animal Health’s Sheep Wormer Checker for advice on which treatments to use and when, to ensure a sustainable worm management plan is in place. Find the tool here: https://www.farmanimalhealth.co.uk/sheep/sheep-worms/sheep-wormer-checker.
[1]https://www.farmanimalhealth.co.uk/sheep/sheep-worms/zolvix-wake-up
[2] SCOPS Internal Parasite Technical Manual
[3] Wales Against Anthelmintic Resistance Development (WAARD) Final Report 2015