[New anthelmintics and new treatment systems for the control of parasitic diseases of cattle in pastures].

Advanced knowledge of the epizootiology of parasitic gastroenteritis and the introduction of new anthelmintics and new application systems allow new strategies to control parasites of cattle on pastures. Ideally, parasitic gastro-enteritis is prevented by evasive grazing, i.e. the animals are driven every two weeks to new and not yet contaminated pastures, and the application of anthelmintics is not necessary. Midsummer treatment is most effective when combined with a move to non-contaminated pastures (Weybridge dose and move system). Following the introduction of the slow-release-devices, the prophylaxis of parasitic gastro-enteritis became much easier. The device, which is usually called bolus, is administered before turnout and it results in an effective reduction of the infection risk throughout the grazing season. Treatment following 3, 6 and 9 weeks after turnout prevents the development of dangerous numbers of infective larvae on the pasture in the second half of the grazing season. This system is known as Glasgow model. The pulse-release boluses follow the same principle and they offer the advantage of application at turnout and of releasing the anthelmintic in full doses at intervals. Treatment at the beginning of housing is only necessary when measures to prevent parasitic gastro-enteritis during the grazing season were not sufficient. All strategic measures reduce the risk of lung worm disease, but they do not prevent lung worm infection completely. On farms with a high lung worm pressure, additional control measures may be necessary. In areas with high risk of liver fluke infection, treatment in July may reduce pasture contamination.(ABSTRACT TRUNCATED AT 250 WORDS)