Contrary to popular believe, sheep producers are being warned against blanket worming all ewes at lambing time due to the widespread resistance to wormers now being detected on farms across the UK.

Iolo White, veterinary partner at Camlas Farm Vets LLP says while late pregnancy and early lactation can present a higher-risk period for ewes, blanket treatment may not be needed, and faecal egg counts (FEC) should be used to assess the level of risk before worming.

“Historically, the advice has been to treat all ewes during the lambing period due to a drop in immunity which can increase the number of eggs shed and level of pasture contamination,” says Mr White.

“However, not all ewes shed high amounts of eggs during this period, with factors such as body condition score, nutrition, foetal numbers and the level of physical stress, all having an impact.”

With anthelmintic resistance presenting a real threat to the sustainability of lamb production, he says a measured approach to worming is a must.

“It’s particularly important to keep an eye on yearling ewes, ewe lambs and bought-in animals, as their immunity to worms may be lower than a healthy home-bred ewe,” says Mr White.

“FEC’s should be carried out every 10 to 14 days during high risk periods, starting three to four weeks pre-lambing or if production and health problems arise, so producers can make accurate worming decisions.”

He says FEC’s are a very useful tool when used alongside vet advice and resistance profiles and help for specific farms determine worming protocols.

Dependent on ewe condition, worming may be necessary between 200 and 400 eggs per gram of faeces. For ewes in good condition with FEC’s within that threshold, it may be worth waiting and testing again in 10 days before treating. However, if several ewes are looking dirty with a low body condition score, treat those specific ewes and then re-test.”

Mr White says use of the latest technology makes FEC testing quicker and easier, with virtually instant results now possible.

“We use the FECPAKG2 from Techion to carry out FEC’s for our clients. Internet connected and image based, testing can be carried out virtually anywhere. It gives us greater confidence in the results, as the images are stored and can be rechecked, providing quality control which we didn’t have with traditional microscope-based system.

“It also allows us to collect, test and receive FEC results very quickly, so that treatment decisions can be made within a few hours. The system is easy to use and some clients with larger scale flocks may find it beneficial to invest in their own FECPAKG2 carrying out FEC’s on farm themselves.”

For farmers undertaking regular egg counts, Mr White emphasises the importance of keeping accurate records, which allows an accurate picture of high-risk fields to be produced. This can then help inform management strategies, for example grazing cattle on certain fields to reduce worm burdens or even taking the decision not to graze sheep on pasture where contamination is very high.

“Another very useful aspect is resistance profiling which determines which wormer group the flock has resistance to, allowing more effective treatment,” explains Mr White.

“Anthelmintic resistance is a big threat to sheep production and the use of diagnostic technology is vital to give producers the confidence to use wormers responsibly,” he concluded.