Physiological and Environmental Factors Affecting the California Mastitis Test under Field Conditions

Open Access
Publisher Website
Google Scholar
Abstract
The California Mastitis Test was used on quarter samples of the milk of individual cows to determine the physiological and environmental factors related to positive reactions. In one experiment involving 1417 cows tested once, 30.6% of the quarters gave positive reactions. In a 2nd experiment involving 339 cows tested monthly for 10 months, 18% of the quarters tested were positive. Older cows showed a markedly higher percentage of positive quarters. Positive reactions increased as cows passed mid-lactation. Seventy per cent of quarters positive at the end of a lactation returned to negative following a dry period. Environmental factors significantly correlated with a high proportion of positive reactors were: Large herd size, low production per cow, improper preparation for milking, inadequate sanitation, and fluctuation of milking machine vacuum during milking.