Effects of natural intramammary Corynebacterium bovis infection on milk yield and composition.

The objective was to assess effect of Corynebacterium bovis infection of the bovine mammary gland on milk yield and composition. Yield and composition of milk from 53 Corynebacterium bovis-infected quarters of 44 cows at four consecutive milkings were compared with those of the contralateral uninfected quarters. Differences between infected and uninfected quarters in milk, fat, and protein yield and in fat and protein content were small and statistically nonsignificant. Numbers of somatic cells were moderately but significantly higher (119,000 vs. 79,000 cells/ml) in infected than in uninfected quarters.