[Fascioliasis in sheep in South-western Jutland (author's transl)].

The frequency of fascioliasis in sheep of south-western Jutland has been determined on the basis of slaughterhouse registration of infected livers over a 5-year period (1969-1973). The average yearly percentage of adult sheep found to be infected ranged from 83.9 to 91.2%, whereas less than 1 % of the slaughtered lambs proved infected. The high infection percentage among adult animals and the strikingly low frequency among slaughter lambs could be explained by the characteristic management system of the marshland: In summer the sheep graze the dike and the foreland on its seaward side, and in winter the animals graze in the marshland. Lymnaea truncatula is not found on or at the seaward side of the dike, whereas it is abundant all over the marshland. Thus the lambs graze exclusively the snail-free area from which they are taken directly to the slaughterhouse. The summer grazing also protects the adult animals as they avoid the massive uptake of metacercariae which normally takes place in fluke infected areas in late summer.