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Liver fluke study on Islay

Moredun scientists, Philip Skuce and Gillian Mitchell, were delighted to be asked by Matt Colston, a veterinary specialist with Elanco Animal Health, and a former Moredun Regional Advisor, to help with a liver fluke study on the Isle of Islay, the southernmost of the Inner Hebrides islands. Islay is typical of the West of Scotland, with plenty of rough grazing and a lovely mild wet climate that favours the mud snail intermediate host of the liver fluke. As a result, farmers on Islay, and mainland Argyll, have had issues with liver fluke in their stock over many years. Routine treatment with the frontline flukicide, triclabendazole, at set times of the year, has been the mainstay of liver fluke control on the island, but this is proving to be unsustainable in the face of changing seasonal patterns of fluke infection and emerging resistance to triclabendazole.

The farm where we focused our efforts was Kinnabus on the beautiful Oa Peninsula, overlooking the coast of Northern Ireland. Kinnabus is managed by the RSPB in order to protect a small population of red-billed chough, which are unique to the Western Isles. It is important that the site is grazed by cattle and sheep as the chough’s main food source is dung beetle larvae, and without grazing livestock, there isn’t any dung! That said, the routine treatment of those livestock for fluke had been shown to have a detrimental impact on the dung beetles and other dung and soil fauna that are key to a healthy farm ecosystem. Farm manager, Stuart Lamont and RSPB Warden, David Wood were keen to optimize their fluke treatment regime and treat ‘as little as possible, but as much as necessary’.

In order to help with this, we conducted monthly faecal egg counts on composite samples from different management groups on the farm, starting in August. There are other arguably better diagnostic tests available for fluke e.g. blood test, coproantigen ELISA, but these are relatively expensive, as they work best on individual animals. We were really looking for a relatively cheap entry-level test that would help us confirm when fluke was present in Stuart’s animals, to help with treatment timing and product choice and to confirm that any treatment had worked. As we have also seen on mainland Argyll, fluke eggs didn’t really appear until well into the winter, several months later than we might traditionally have expected to see them. We were also able to confirm that the fluke on Kinnabus were still resistant to triclabendazole, several years after the initial report, and so could advise on a better alternative.

This study has shown that, with a bit of simple testing, it is possible to better understand what’s happening with fluke on-farm, and to make informed decisions about if/when to treat, what product to use and whether it worked or not! As a result, Stuart and David were better able to sustainably manage Kinnabus, a win-win for the livestock, the chough and the environment.

We were delighted that the study was selected to feature at the Royal Highland Show RHASS President’s Initiative, ‘The Science behind our Food’, and also featured in a recent episode of SAC’s Farm Advisory Service FASTV series.

The only disappointing aspect from our point of view is that we didn’t actually get across to Islay to sample the animals (or any of the island’s other produce!).

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