| observations on the epidemiology of dictyocaulus viviparus in north west england. | a five year ley pasture was used as a source of natural infection with dictyocaulus viviparus for cattle in anthelmintic trials. pasture larval counts, faecal larval counts of permanently grazing calves and lungworm burdens harboured by tracer calves were monitored in three grazing seasons to assess the pattern of infection. carrier calves were introduced at the beginning of the grazing season in the first two years of the study but not in the third. in the fourth year the pasture was subdivided ... | 1982 | 6210944 |