Sheep farmers are being advised to be on their guard against nematodirus and stomach worms as warm and wet weather cause egg counts to spike.

Sheep farmer, Tom Carlisle, from Skipton, North Yorkshire, saw nematodirus egg counts in his lambs reach 770 eggs per gram (epg) at the end of May, and worm egg counts reached 220.

Carlisle had treated his lambs with a white drench in April as a faecal egg count test highlighted a low level of nematodirus, and weather conditions were ideal for a mass hatch.

Due to regular faecal egg count (FEC) testing, Carlisle, who has more than 1,000 lambs on the ground, was able to prevent a problem using a white drench to treat for nematodirus before any symptoms were present.

Commenting, he said: "You never know what your worm burden is like until you do an egg count. When you see any physical signs, the damage is already done. It shows the importance of regularly testing, so you can use wormers responsibly and when needed."

He plans to conduct another egg count shortly to see whether any treatment is needed to manage worms.

"The weather has been warm and wet here, providing ideal conditions for worms. However, we've not seen any mucky bums yet - the idea is to nip any burdens in the bud," he added.

But Zoetis vet, Ally Anderson, said that farmers need to be ready for the worm challenge.

With warm and wet weather conditions persisting, there could be a high burden of parasites, which could impact on lamb productivity.

"It is important to monitor your lambs to check when treatments are needed. This can be done through a combination of taking FECs and monitoring live weight gain. This information will help with the decision around which animals would benefit from a treatment.

“Carefully consider which product you are planning to use. While white wormers are a good choice for treating nematodirus, we know there is a high level of white wormer resistance in the UK.

"If you are not sure what the level of resistance is to different actives on your farm, your animal-health advisor will be able to advise you on how to investigate and select the correct product required later on in the season.”

She added:

"We are also seeing high worm egg counts from many of the farms FEC testing as part of the Parasite Watch Scheme. For example, faecal worm egg counts of 770 were reported from a farm in Angus in mid-May, which is quite early for so far north.

"High counts have also been seen in Northern Ireland, Dumfries, as far east as Norfolk and down to West Sussex and Herefordshire," she said.