How many seconds after mixing should the California Mastitis Test (CMT) be read?

The California Mastitis Test (CMT) is a valuable tool used to detect subclinical mastitis in dairy cows by assessing the somatic cell count in milk. The timing of the reading is crucial for obtaining accurate results. The test should be read 20 seconds after mixing the reagents with the milk sample.

This specific duration allows adequate time for the reaction to occur, which is visually observed by the formation of a gel or a change in consistency that indicates the presence of somatic cells. Reading the test too early or too late could lead to misinterpretation of the milk quality and health status of the udder.

While other time intervals such as 10, 15, or 30 seconds might seem plausible, they do not allow for the optimal reaction time that ensures reliable results. Therefore, 20 seconds is the standardized timing supported by the protocol for the CMT.