Early identification of mastitis gives you the best chance of cure, and of preventing persistent problems. Clinical cases will have obvious signs, such as clots in the milk or a swollen quarter, but what about the subclinical cases? These have no signs at all, other than a high somatic cell count (SCC). The California Mastitis Test (CMT) is a quick and easy ‘cow-side’ test that is useful for detecting subclinical mastitis by estimating the SCC of the milk. The test works on the principle that mixing milk with a reagent causes the somatic cells in the milk to rupture. When the DNA is released from these cells, it coagulates and forms slime-the more cells there are in the milk, the more “jelly-like” the result!

It is good practice to check all cows and 1st lactation animals with the CMT before including their milk in the bulk tank for the first time-that way you can be confident that any problem cows are picked up early, before they cause more trouble.

3 easy steps!

1.    After discarding the first 3-4 squirts of foremilk, collect 2-3 squirts of milk from each quarter in each separate well.

2.    Add an equal amount of reagent to each well. Swirl the paddle gently, mixing for 10 secs.

3.    Look at the consistency of the fluid in each well (not the colour), and record the amount of gel reaction that occurs within 20 seconds (from none to almost solidified).

CMT kits are available from most co-op retail stores and veterinary clinics and are very inexpensive. Replacement bottles of reagent can be purchased separately. This is one of the best investments to make in your dairy-go get one and start practising!

What do the results mean?

Results are generally categorised as follows: negative, trace, 1, 2, 3.
This test is subjective! i.e. what you score as 1, your neighbour might score as a 2.
Remember-the important thing is that any positive reaction (1,2 or 3) indicates a high SCC in that quarter.
To become accurate and consistent, practice on cows with a known high SCC.

For more information, see the CellCheck Farm Guidelines for Mastitis Control, or see their YouTube video.