Livestock medicine producer Zoetis is urging sheep farmers to be on high alert for worm and fluke risks in their flocks this autumn.

Results from the farms involved in the company’s parasite watch scheme at the end of August revealed worm egg counts in lambs varying from 70 to over 700 eggs/gram, with an average of 380 eggs/gram.

Zoetis said these results highlight the importance of faecal egg counts (FEC) on an individual farm and at a group level.

Together with growth rates, they are a good indication of the need for treatment in lambs, the company said.

Zoetis vet Patricia van Veen said the extreme and variable weather is making predictions difficult and is likely contributing to localised spikes in FECs.

Zoetis said its parasite watch data from previous years shows the parasite challenge remains a real risk into the autumn.   

“Fluke is more challenging to monitor through FECs at this time of the year, as the time between infection and egg production, known as the pre-patent period, is 10-12 weeks,” van Veen said.

“During this period, the early immature migrating larvae do a lot of damage, causing the disease known as acute fluke in any age of sheep.

“Ewes and rams also need monitoring in the approach to tupping as fluke burdens could impact their condition and conception rates.”

Parasite risk

Sheep farmer John Yeomans, who farms near Newtown, Powys, and is one of the parasite watch monitor farms, said he treated his animals earlier this year due to the parasite risk and challenging summer.  

Yeomans tups 530-550, mostly Beulah ewes and 170 ewe lambs each year, bringing them back to the home farm in October and returning them to the hill in December until lambing.  

“Our farm is heavily stocked, with the ewes grazing high-up, so we demand a lot of them,” he said.

“Over the past decade, we have noticed that fluke can pose a real risk on our farm, sometimes resulting in dead sheep.

“We have done post mortems on them before and found them to be full of fluke.”

Yeomans said he not only monitors worms and fluke by regular testing but is also trying to do more targeted worming based on weight gains in lambs.

“We must use medicines responsibly to safeguard their use,” he said.

Van Veen said it is important that farmers work with their animal health provider to select the best product, particularly when there is a mixed parasite burden in their lambs.

“Carefully consider which product you are planning to use,” she said.

“Your animal health advisor will be able to give you the best advice on which products to choose.”