Worldwide, mastitis is still one of the most important diseases in the dairy sector.
Being a multifactor disease, caused by multiple pathogens, mastitis is difficult to control.
Mastitis not only affects the health of milk-producing animals, having consequences for the profitability
of dairy farms, it also affects the welfare of the animals.
Moreover, mastitis negatively influences the quality of the milk with consequences for the dairy
processing industry. Thus, mastitis affects a large part of the dairy production chain.
California Mastitis Test (CMT)
The California Mastitis Test (CMT) is a rapid, accurate, cow-side test to help determine
somatic cell counts (SCC) in a specific cow. The test was developed to sample
individual quarters to determine the presence of subclinical mastitis. A cow with
subclinical mastitis does not have abnormal looking milk or other clinical signs such as a
swollen or painful udder. The test can also be conducted on bucket and bulk tank milk
samples to help determine somatic cell counts (SCC) of the entire herd.
How to Perform the Test: (See figures 1-5.) A small sample of milk (approximately ½
teaspoon) from each quarter is collected into a plastic paddle that has 4 shallow cups
marked A, B, C and D. An equal amount of CMT reagent is added to the milk. The
paddle is rotated to mix the contents. In approximately 10 seconds, read the score while
continuing to rotate the paddle. Because the reaction disappears within 20 seconds, the
test must be read quickly.
How to Read the Results: The CMT reagent reacts with the white blood cells and the
mixture thickens or gels in proportion to the amount of infection present. To become
accurate and consistent, practice this test on cows with a known SCC.
||Average Somatic Count
(Cells per millilitre)
|Description of reaction
||No thickening, homogeneous.
||Slight thickening. Reaction disappears in 10
||Distinct thickening, no gel formation.
||Thickens immediately, begins to gel, levels in the
bottom of cup.
||Gel is formed, surface elevates, with a central peak
above the mass.