California Milk Test (CMT)

About - Instructions - Results

This is a cow-side test to get an idea about individual quarter cell counts and can be very useful when deciding whether to treat quarters for mastitis or investigating high somatic cell count (SCC) cows.

Milk always contains some cells. There can be small numbers of white blood cells and dead milk producing cells from the glandular tissue. The SCC of a healthy, uninfected udder lies below 200,000 cells per ml. Cows which have an infected udder or damaged glandular tissue will have a rapidly increasing SCC. SCC is an accurate method of assessing udder condition.

SCC can be monitored monthly with milk recording, usually all four quarters are mixed together for this e.g. NMR Milk Recording. The CMT can be used along side this or on it's own. CMT gives a result for individual quarters, quickly and easily with the cow infront of you. The CMT is also economical.

High SCC milk comes from infected udders and these cows will have reduced milk quality, reduced milk yield, costs of treatment and reduced milk value. This is also a common reason for early culling of cows.

Through early, accurate identification of infected udders, treatment can be given earlier and there is a greater chance of successful treatment and return to lower SCC and increasing yield. Therefore more likely to remain in the herd for longer.

When the SCC is greater than 250,000 cells per ml, there is an obvious reaction in the CMT result. The reaction is more and more obvious the higher the cell count. The change in consistancy of the fluid can vary from slight mucus substance to an almost jelly-like consistancy where the indicating colour change becomes more obvious.

You will require 1 CMT Paddle (Tylan 200 paddles available from the Office for free); CMT Test Liquid (about £7 + VAT for 500ml); and paper or pad to record results.


About 12ml of liquid allows the test to be completed on all four quarters in less than one minute.

  1. Squeeze a small amount of milk (about 3ml) out of each teat into the corresponding quarter of the paddle. Avoid frothing the milk.
  2. Tip surplus milk out of the paddle, leaving only 2ml of milk in each segment (use the 2ml line as a guide)
  3. Add about 3ml of CMT Liquid to each segment of the paddle.
  4. Mix well by gently moving in a circular motion.
  5. Record the reaction of each quarter
  6. Empty and wash the paddle in water after each use



The consistancy of the mixture of milk and liquid remains unchanged or will not change significantly. Cell Count (SCC) below 250,000 cells/ml.

Weak Positive

The mixture changes to mucus. Cell count between 400,000 and 1,500,000 cells/ml. Milk yield will be decreased.


Unmistakable muscus formation, the mixture will slow down when agitated. Cell count between 800,000 and 5,000,000 cells/ml. Milk yield will be markedly deceased.

Very Positive

The mixture turns to thick mucus, almost jelly, no longer liquid, lumps may develop. Cell count above 5,000,000 cells/ml. Considerably reduction in milk yield. This reaction requires veterinary attention.

If you would like to get a kit or would like a demonstration please contact the Office.


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