High incidence of clinical mastitis due to Staphylococcus aureus in two dairy herds with low milk cell counts

Five dairy herds with a high incidence of clinical mastitis were investigated. Two of these herds had a high incidence of mastitis caused by Staphylococcus aureus yet had a relatively low rolling mean cell count. The mean cell counts of samples from clinical cases submitted by the dairymen from these two farms were significantly lower than the counts of similar samples submitted from the other farms. It is suggested that a possible explanation of the low cell count on these two farms was the proficiency of the dairy-men in detecting clinical mastitis.