Sheep farmers in the South West are being advised to find out what the worm challenge is on their farm, after reports of mixed worm infestations from faecal egg counts.

Farms involved in the Zoetis Parasite Watch scheme have been challenged by different types of worms at the same time, which is important to know for treatment purposes.

Zoetis account manager Ifor Jones urges farmers to find out whether the challenge is just from Nematodirus or other stomach worms before treating.

Ifor said: "If you’ve got a mixed infestation then you need to be confident the drug you are using will treat against both Nematodirus and stomach worms.

“The most dangerous situation is when a wormer is only 60 to 90 per cent effective as you won’t see any visual resistance issues in your lambs, but you won’t be maximising their growth potential.

"You will also be allowing resistance to build up on your farm.”

“You need to find out what drugs are working on your farm and what are not in order to protect the farm for future generations."

Vet Emily Gascoigne of Synergy Farm Health, agrees with Mr Jones and urges farmers to carry out post drench check tests.

“I advocate at the least doing post-drench egg counts to check that egg counts have been eradication.

"It is a good tool to build up a picture of what is happening on the farm.

“If you are drenching to preserve performance why wouldn’t you want to check the product is actually working.”

For a yellow drench faecal egg count reduction tests can be taken seven days post treatment and for all other wormer groups after 14 days.

Vet Dave Armstrong from Zoetis says this spring has seen a mixed challenge by worms, with a high challenge being reported on some farms and low on others.

Nematodirus seems to have been less of an issue on farms in the South, which could be due to a number of reasons.

He said: “It could be that farms lambed earlier down south so missed the peak of the challenge, or whether a micro climate element is playing a part.

"The mixed burden of worms has shocked a few people and altered treatment strategies.”