California Mastitis Test Reactivity and Bacterial Invasions in Quarters Infected with Corynebacterium bovis

Investigations were conducted into the effects of infections of Corynebacterium bovis on California Mastitis Test reactions and intramammary invasions by typical mastitis pathogens. Mean mastitis score for milk from quarters shedding C. bovis was 1.1 (1 to 4 basis) compared to .5 for milk from uninfected quarters. Isolations of typical mastitis pathogens were significantly lower among each of two groups of quarters which were shedding C. bovis than among two groups which were uninfected before the experiments.