Routinely treating sheep and cattle for liver fluke has led to overuse of treatments, increased resistance and costs to farmers and the environment, which could be avoided through testing.

A seasonal study carried out on Islay, has demonstrated that treating ‘as little as possible, but as much as necessary’, can deliver win-wins for animal and environmental health.

The fourth in a series of case studies, developed as part of the RHASS Presidential Initiative (PI), exploring the science behind food and drink production, will look at how a collaboration between Moredun Research Institute, Elanco Animal Health, RSPB and Islay farmers has come up with a plan to boost animal welfare and reduce flukicide resistance.

For many years, farmers have routinely treated their sheep and cattle for fluke at specific times of year, but overuse of treatments has changed parasite seasonality and reduced the efficacy of certain products. Scientists have been working with farmers and the pharmaceutical industry to advocate for more testing and evidence-based decision-making, to minimise the impact on animal health, welfare and productivity as well as minimising any potential environmental impact.

Moredun had been hosting active discussion groups focusing on mitigating the potential for negative environmental impacts associated with treating grazing animals for internal parasites and alongside Islay vets and Liverpool University, was involved with undertaking faecal egg counts from sheep and cattle on study farms to establish the presence of liver fluke on the island. By doing this, they were able to better understand when and where animals were picking up fluke infection.

Stuart Lamont stood as one of five farmers involved in the testing programme and farms 100 Highland cattle and 400 Blackface ewes, grazing over 2000ha of coastal grassland, in-bye, heath and peatland.

Before taking part in the testing programme, Stuart had routinely treated his sheep at set times throughout the year, but his test results came back to show very low levels of fluke in the summer and autumn, and he was advised not to treat until January.

“By listening to the science, we have been able to make informed decisions about when to treat our livestock, which has led to benefits for animal welfare, as well as significant chemical savings.

“I’m now not having to unnecessarily handle my sheep to run them through a race every six weeks and by treating more sparingly, it means the products are more likely to work when we need to use them," he added.

Moredun Parasitologist, Philip Skuce, added that there is a careful balance to be struck between responsible treatment and conserving biodiversity on farm.

“On Islay, we were looking at how we could ensure optimal treatment for livestock whilst also addressing issues around product resistance, improving soil health, and supporting local wildlife,” said Philip.

“During the project, we found that farmers were very worried about liver fluke, due to Islay’s mild wet climate which favours the fluke’s life cycle, so were often treating prophylactically with flukicides but this approach doesn’t work particularly well,” explained Philip.

“Through conducting monthly faecal egg counting on selected groups of animals, we found that the timing of liver fluke infection was well off where we would have historically expected to see it, due at least in part to changes in weather patterns in recent years.

"We recommended routine faecal testing which would establish when and where an animal had picked up liver fluke and what treatment would be most effective. We also tested how effective any treatment had been. This allowed the farmers to optimise treatments, and save money in the long run, as well as limiting the risk of developing flukicide resistance,” he continued.

“There is increasing pressure on the agricultural industry to reduce chemical usage and the most simple and effective way to do this is to ‘test, don’t guess’ and with patterns of parasite epidemiology shifting, more than ever scientists need to be monitoring these changes and bringing farmers along with us.”

Commenting on the study and testing carried out, and why the RHASS Presidential Initiative to highlight the work on animal and environmental health, RHASS President Ian Duncan-Miller commented:

"The application of science to an everyday problem on Islay has shown a quite remarkable breadth and diversity of gains, and shows how really understanding the long-standing challenges will lead to benefits across the board.

“On a wildlife reserve, the priority is obviously the naturally occurring creatures, and this research has demonstrated the importance of science around the grazing livestock to the plants and other animals," he stated.

Matthew Colston who works as technical consultant for animal health company Elanco, which supplies a range of parasite control products for sheep and cattle, also got involved with the Islay project in order to help demonstrate that fluke treatments can be accurately targeted, minimising the risk of developing resistance through overuse of products, which would leave farmers without an effective option for sustainable fluke control.

“Previously farmers have been taught to routinely treat animals for parasites but as the science has developed, it has showed us that although initially this is a great idea, we are driving development of resistance in all livestock parasites in the way we are using these products," he explained.

“If resistance levels continue to rise, then we won’t be able to farm animals in high-risk fluke areas, as animals will die before we can treat them. Two of the farms on Islay had little efficacy with TCBZ, so it was vital we made them aware of the risks of treating with the same active, time after time.

“Worms and fluke are an overlooked drain on farming in Scotland, impacting production efficiency on every stock farm every year. The reason farmers aren’t adopting testing protocols more quickly is because most farmers think what they are currently doing is the best way to control these parasites. Fluke is a moving target, and we need to be using science and evidence to ensure we are making the best decisions for animal health and welfare as well as the environment," concluded Matthew.