Antibody response to Mycoplasma bovis of calves introduced to a farm contaminated with the organism.

Antibody against Mycoplasma bovis in sera of 48 calves introduced to a farm, in which calf pneumonia associated with M. bovis had been occurring in the last 3 years, was detected by an indirect hemagglutination test. Significant rises of antibody titers in sera of calves belonging to the groups A (16 calves) and B (14 calves) were recorded by day 60 post-introduction. On the other hand, a significant increase of antibody titers of 18 calves in group C, which had been administered antibiotics as a preventive therapy, was demonstrated at day 248 after arrival. These results indicated that the spread of M. bovis infection occurred easily on the contaminated farm, and a preventive therapy could delay the outbreak of calf pneumonia associated with M. bovis.