Pictured: Dr Philip Skuce, Senior Research Scientist at the Moredun Research Institute.
Following confirmation that liver fluke had caused ill-thrift in lambs on Cluny, the Moray and Nairn Monitor Farm near Forres, the recent meeting discussed fluke in sheep and cattle, and methods to control it.
Cluny is part of the national programme of monitor farms, led by Quality Meat Scotland (QMS), and is a 1,060 acre unit, farmed by Robbie Newlands, his wife Kirsty and his father, also Robbie. There is a suckler herd of 170 plus cows and a flock of 650 Scotch Mule ewes. All progeny, sheep and cattle, are finished.
Mr Newlands told the group “lambs which have been treated for fluke have really thrived and look significantly better. Thanks to the fluke, we’re unlikely to get any lambs away until around the end of October. Next year we’ll definitely treat all our lambs in July.”
Dr. Philip Skuce, a Senior Research Scientist at the Moredun Research Institute, explained the geographic migration of fluke and its life cycle to the community group, as well as outlining measures farmers can take to control the parasite.
Fluke, once regarded as a problem of the wetter and warmer areas in the west, has spread dramatically over the last 10 to 15 years, and is now also found in the east of Scotland.
Fluke damages livers, reduces livestock performance, impacts on fertility and is sometimes fatal. Overall, it is estimated to cost the Scottish livestock industry in the region of £50 million per annum.
Flukes are parasitic flatworms which grow to about an inch in length. They infest the livers of various animals, including sheep, cattle, goats, pigs, rabbits, hares, deer and horses. Their life cycle is complicated, involving mammalian hosts and intermediary snail hosts.
Understanding the fluke life cycle, which is influenced by climatic conditions, is fundamental to controlling this costly parasite.
Adult flukes live in the bile ducts of sheep and cattle, where they can shed up to 50,000 eggs per day, which are passed in faeces onto pasture.
At temperatures above 10 deg C, a larva develops inside the egg.
Once hatched, within a few hours the larva, unable to feed itself, needs to penetrate a mud snail, which lives in moist areas and slow-moving water courses.
Over a period of six to eight weeks the fluke larva inside the snail multiplies into hundreds, sometimes thousands of little tadpole-like creatures, which bore out of the snail. They rapidly become infectious cysts, attaching themselves to blades of vegetation or herbage until ingested by a grazing animal.
These cysts can survive for approximately a year on pasture, depending on the prevailing weather conditions.
Once ingested, the cysts hatch in the animal’s intestine, releasing immature fluke which penetrate the gut wall and locate the liver. The young fluke then cause severe liver damage as they travel through the liver to the bile ducts, where they mature into egg-laying adult fluke, re-commencing the life cycle.
Dr Skuce reminded the community group of the crucial role of the mud snail as without it the fluke life cycle could not continue.
He recommended grazing livestock on well drained pasture and fencing off wet areas, to help keep livestock from likely mud snail habitats, especially during high risk periods.
The same fluke affects sheep and cattle, so mixed grazing should be avoided if possible, and cattle should be included in treatment programmes on such farms. An additional and largely unavoidable complication is that wildlife, e.g. hares, rabbits and deer, also harbour and spread fluke.
If the farm is free of fluke, minimise risks of importing it by treating in-coming stock before they join the flock or herd.
Dr Skuce emphasised that there are no “blue prints” for fluke control and that farmers need to remain vigilant and tailor control strategies to conditions on their own farms.
Things to consider include the farm and neighbouring farm’s history, abattoir returns which provide liver fluke information, the vet’s local knowledge, climatic factors, plus regular monitoring to establish whether or not stock is affected.
Once fluke is suspected, it is important to use the appropriate anthelmintic at the correct treatment intervals.
Dr Skuce explained that no single flukicide kills all stages of fluke, and emphasised the importance of establishing the level of challenge and stage of fluke being targeted, ranging from adult flukes in the bile duct, to very young immature flukes in the liver.
General guidance for autumn treatment of housed animals is to wait until two weeks after housing, during which time there has been no ingestion of fluke cysts through grazing, then treat with Triclabendazole, which targets all stages of fluke except early immature.
For winter-housed stock, to clear them of mature fluke prior to turn-out, (thereby preventing shedding of eggs onto grass), there is a range of products with active ingredients which target only adult fluke.
There are no flukicidal drugs licensed for use in lactating animals, so dairy cows can only be treated in the dry period, just before calving.
Because of the complexities of fluke, Dr Skuce recommended that farmers consult their vets to ensure the most effective treatment strategy.
Of concern to the livestock industry is the increasing number of reports of lack of efficacy of Triclabendazole (TCBZ), the active ingredient in a number of leading flukicides.
With current tests to determine flukicide efficacy not totally reliable, it is impossible to definitely establish whether or not a flukicide treatment has worked.
However, a recently developed test which is currently being trialled by the Moredun, is yielding promising results. The new test detects tiny quantities of fluke secretion in animal faeces, and is simpler and more reliable than traditional fluke egg counting. When used after flukicide treatment, this new test should provide an accurate and immediate indication as to whether or not there is fluke infection, thereby determining the success of the treatment.
The only animals currently on the Moray and Nairn Monitor Farm which have not been treated for fluke are this year’s calves. The farmer, Robbie Newlands plans to blood test these calves for fluke antibodies. If the results are positive, the calves will be treated with the appropriate flukicide. Faecal samples will then be taken for the Moredun to trial the new test.
The next Moray and Nairn Monitor Farm meeting will be on 7 December 2011.
For further information, please contact either of the joint facilitators:-
Peter Cook, Telephone 01467 623222 or 07774 160246
Colin Anderson, Telephone 07500 012883
For general information on Monitor Farms, plus detailed reports of meetings: www.qmscotland.co.uk/monitorfarms