24 November 1995

Fluke challenge still cause of big losses

By Robert Davies

DAMAGING losses are still result- ing from poor liver fluke control.

Dr Sharon Parr, of Dublin University Faculty of Agriculture, told the Sheep Health and Welfare 95 conference, Malvern, Worcs, that drugs active against immature fluke had cut deaths. But losses still occurred, even where there were no signs of fluke infection.

Traditionally flukicides were used therapeutically, to remove fluke burdens from autumn to early spring, when stock were at most risk. This was adequate in years of low-to-average risk and more than adequate on areas where fluke was a minor problem.

But this method of dosing allowed the liver fluke to complete its life cycle, perpetuating the risk of disease. The alternative was preventative dosing. That involved dosing to prevent fluke eggs from being passed on to the pasture during the spring and summer, when the secondary host snails were active and the weather favoured the parasite. It involved treating all sheep and cattle three times at eight-week intervals, mid-March to early April, May to June and again in July to August.

Dr Parr warned that exceeding the eight-week period would allow fluke eggs to be passed on to pasture. The approach should be repeated in the second year. But by the second winter fluke levels should be low enough to reduce treatments to a November and January dose. &#42

&#8226 Preventative dosing to prevent fluke eggs being passed on to pasture.

&#8226 Treat all sheep three times at eight-week intervals; mid-March to early April, May to June and July to August.

&#8226 Repeat treatment in 2nd year.