Don't count on drought to dry out fluke

The UK's cattle herds are still at risk from fluke infection this year, a leading animal health company has warned producers, despite the recent talks of drought in the south-east and other areas of the country.

Met Office data shows that the average rainfall recorded in the UK between December 2005 and February 2006 was 196.7mm, 40% less than the long-term average. Now Merial Animal Health is concerned that because fluke is traditionally associated with wet periods, the current dry conditions might give producers a false sense of security about liver fluke disease.

"Producers should be aware that the development of the fluke lifecycle is heavily influenced by rainfall in the previous year," says Helen White, Technical Services Manager for Merial.

"In the UK, the immature stage of the fluke parasite hatches in the spring, which means that above-average rainfall at any time during May to July will provide optimum conditions for its development.

"The miracidium continues its lifecycle within a mud snail intermediary host over the summer, before infecting cattle and sheep in late summer and autumn," Ms White explains.

"And although much of the summer saw below-average rainfall, July 2005 saw conditions wet enough for fluke proliferation," she notes.

But prediction of the disease, which can reduce cattle liveweight gain by up to 10% and depress milk yield by up to 15%, is not straightforward. "Infection from season to season depends upon a variety of different factors including the climate and incidence of fluke in the previous year.

"Any wet areas on farms present the greatest risk and can remain so even in dry summers," she points out.

"An animal's production potential is already affected the moment it's infected," she warns. "No flukicide can repair liver damage. Outwintered cattle should be given a spring fluke treatment to counter any infection they've picked up from pasture, whilst cattle housed during the winter should be dosed in the spring to reduce pasture contamination, even if they were dosed at housing.

"But if producers are in doubt about whether they should be protecting their stock against fluke, their vet is the best source of advice."

Ms White reminds producers that monitoring liver condemnations from the abattoir will provide an additional, and valuable, indication of the level of fluke on-farm."