EN
The bactericidal titre against Escherichia coli was deter- minned in sera of eighty male Lowland-black-and-white calves, 9—10 weeks old, 80—90 kg of body weight in four experimental groups, 20 animals of each. The animals were kept in a litter calf shed (group I), grate calf shed of the Bisprol type (group II), pasture (group III) or in an adapted grate calf shed (group IV). In each group two subgroups were formed: A — calves from individual farms and В — from state farms. The highest bactericidal titres were found in sera of calves from the subgroup В groups IV, III and I, the lowest in sera of animals from the subgroups A and В group II a and the subgroup A of the group III. The test is very useful to evaluate the effects of environmental conditions on animals. Due to its simplicity it can be used in a field veterinary practice.