Evaluation of the California Mastitis Test for Screening Dairy Cows for Intramammary Infection at Calving

Abstract

Udder health management programs at dry-off and during the dry period are essential to control and prevention of mastitis in dairy cattle. Knowledge of the prevalence of subclinical intramammary infection status at calving, and the specific pathogens involved, allows producers to evaluate effectiveness of these udder health programs. However, milk sampling and culturing all cows at the time of calving can be expensive and time consuming, and has not been widely adopted by the industry. California mastitis test (CMT) has not been recommended for use in recently fresh cows. This study examined the use of the CMT for selecting quarters in fresh cows for further bacteriological examination to identify the presence of intramammary infection. Cut-points for defining a positive CMT test and length of time post-calving were evaluated.