The summer of 2012 has been widely accepted as one of the wettest on record and the cumulative effect of several wet summers is resulting in liver fluke, always considered a problem in the west, emerging as a major concern for sheep and cattle farmers everywhere.
Liver fluke was traditionally confined to wet areas where the mud snails which host the fluke larvae thrive. However, the increase in wet areas on farms and increased stocking densities has allowed fluke to spread.
With a high rate of re-infection and some instances of flukicide resistance being reported, farmers need to be aware of fluke on the farm and treat it accordingly. That was the message from Philip Skuce of Moredun Research Institute near Edinburgh, when he addressed the community group of the Peeblesshire monitor farm at Hundleshope, near Peebles.
Since the inaugural visit, sheep and cattle had been tested for the disease and the results had shown there was a fluke problem on the farm which, while not acute, needed some urgent attention.
The sheep had all received a fluke drench and blood samples had been taken and tested for anti-fluke antibodies, which had been found to be present. As the antibodies persist for around 10 months, it was difficult however to determine if the infection was new or had been carried over since last season.
The challenge for the community group of around 40 farmers was to come up with a suitable programme which the host farmers, Kate and Ed Rowley, could put in place as soon as possible to tackle the problem. This initiated an exchange of ideas within the group.
Dr Skuce explained the complicated life-cycle of liver fluke which starts with eggs deposited in sheep and cattle faeces. These hatch on pasture to release a type of larval stage (or miracidium) looking for its mud snail host which then becomes infected.
The snails then deposit infectious fluke cysts on the grass stalks, which are eaten by grazing livestock. The young fluke hatch out in the intestine, migrate to the liver and eventually establish as egg-laying adults in the bile duct system of the liver, starting the cycle again. This cycle takes the best part of six months to complete and is very dependent on the prevailing weather conditions.
Flukicidal products containing triclabendazole (TCBZ) are the most effective way of killing the majority of immature fluke and are therefore the most effective method of protecting stock in the autumn. It is, however, important to determine what stage of fluke is present in stock at risk and treat accordingly.
Animals can be moved either to drier ground, stubble or brassica growing fields or indoors to help reduce the potential for re-infection. It may also be beneficial to fluke drench again in the spring to kill any adult fluke which can grow to the size of a cornflake and decimate the liver of a sheep to the point of hemorrhage and death.
Fluke often goes undetected in cattle but is responsible for considerable sub-clinical disease and production loss. Dr Skuce also mentioned the recent emergence of rumen fluke in Scotland. This has been linked to flooding events and has been reported to cause disease and death in young stock, both sheep and cattle.
The variation in withdrawal periods of fluke products and the implication of these were also taken into account as the main focus at this time was finishing lambs. Bearing this in mind, it was decided that the lambs, which are now housed, would be split into two groups, following the next draw for market. Those which were lighter or in poorer condition would be contained in one group and dosed again for fluke.
This would not only allow monitoring of the fluke issue but also allow more eating space for the smaller lambs and reduce the incidence of “bullying” at the trough. Lambs would be finished at lighter weights which would compensate for the cost of the feeding intake. The group was encouraged to access further information on fluke control by visiting www.scops.org.uk
The blood analysis results also showed a lack of selenium, in both the hill and cross ewes. Although the ewes were in good condition, this was most likely a result of poor uptake from the grass, again due to the wet season. A sample group had been dosed with a selenium/copper/cobalt bolus and a further assessment would be made of both groups at scanning time with results compared at that point.
The next meeting will be held towards the end of February.