A project carried out in Wales has detected wormer resistance to one or more wormers groups on 98% of participating farms.
The initiative, which was funded through the Farming Connect Advisory Service, uses a flock Faecal Egg Count Reduction Test (FECRT) to establish whether resistance exists to anthelmintic drenches in flocks.
Last year, 49 sheep farms made use of the service, with testing carried out between June and November.
Sampling packs were provided by parasite management company Techion, and Faecal Egg Counts (FECs) were carried out on pooled dung samples – readings of around 500 eggs per gram (EPG) were needed to start the process.
FECs were taken from at least 90 lambs that had not been wormed for at least four weeks.
Once this parameter was set, lambs were split into four treatment groups of 20 lambs each.
They were dosed under strict protocols with either a white drench (benzimidazole), yellow drench (levamisole), clear drench (macrocyclic) or moxidectin.
A sample was taken from each lamb – and was repeated between seven and 14 days later – depending on the type of drench used.
The samples were then sent to the lab to assess the efficacy of that wormer group.
The results showed across the participating farms a 98% resistance to one or more wormer groups.
Speaking about the results, sheep specialist John Hadwin of JH Agri Consultancy said: “At first sight this seems worrying, but because the testing is relatively sensitive and accurate, it means that on many farms we are identifying resistance in the early stages.
“In some ways, it’s good news for the farmers involved, because it means if they are careful and take advice, they can maintain good levels of worm control going forward.
“The results from last year have shown that there is an issue with wormer resistance in the industry and now we need to act.
“This project, I’m hoping, is helping farms to get a handle on their situation and is encouraging people to follow sustainable control of parasites in sheep (SCOPS) principles.
“Hopefully, this will encourage farmers to work closely with their vets or animal health advisors in formulating a robust flock health plan,” he added.
“Overuse of wormers in the past has not only led to resistance developing but has added to cost of production.
“Time and labour are among the highest costs on sheep farms. If you don’t need to be drenching lambs, why do it?
“When farmers are pushed for time, lambs are sometimes dosed simply because they had been gathered for another job.
“By planning ahead, and carrying out a FEC before handling, we know if the lambs actually need worming,” John concluded.
A main element of the Farming Connect project is to support farmers, identify resistance and to put strategies in place to maintain wormer efficacy where possible, while also improving worm control.