This thesis comprises a series of studies carried out (1) to review the literature on parasitic gastroenteritis and bronchitis with special emphasis on epidemiology, immunity and control methods (2) to determine the influence of anthelmintic prophylaxis in calves on their subsequent immunity to Ostertagia, Cooperia and Dictyocaulus as yearlings (3) to assess the parasitological status of adult dairy cattle and (4) to compare the efficacy of several techniques used in these studies
