EN
Gamma globulin content, complement haemolytic activity and serum bactericidal properties were investigated in 24 beef calves showing various stages of bronchopneumonia caused by Mycoplasma organisms. The lowest complement and serum bactericidal activities were observed during an acute stage of bronchopneumonia, as compared to calves with latent form of the disease. At the end of the observation (3.5 months) when the disease became chronic, the activity of the examined parameters was similar in all groups. Gamma globulin content showed no differences depending on the disease stage.