Introduction: California Mastitis Test

Hi, my name is Grady Moorse. I have been working on my family’s dairy farm for numerous years. I am going to show today how to tell if a cow’s milk is full of bacteria and if it should or should not go into the bulk tank using a simple test. I am going to show you how to do this in six easy steps. Doing this test can save a whole farm's milk from having to be dumped down the drain.


First, you will need to gather all of the materials needed. They include a CMT test kit, in this kit, in the test kit there is a paddle, a bottle of California Mastitis Test reagent, latex gloves, a cow, milk, and a small pail to milk some milk into, paper towels.

Step 1: Put Gloves On

To start put the latex gloves on. When doing this, it will be a protector from mastitis but more importantly, protect other cows from having mastitis. It is important that the gloves are only used for that certain cow. A cow with mastitis needs to be treated urgently if the test comes back positive. Not throwing the gloves away and touching a different cows udder can result in the bacteria leaving the gloves and entering the other cow’s udder.

Step 2: Clean Each Teat

Then take a clean paper towel, and with one clean each teat. Clean each teat with a paper towel as there may be bacteria on each teat. It is important to get the whole teat cleaned off before the next step. Baby wipes can also be used but paper towels will be more cost-effective for this step. A paper towel wet down with water can also be used.

Step 3: Strip Each Teat

Now take the small pail and milk three to five squirts into the pail from each teat. This is to get the milk out that has been sitting in the teat since the last milking. The milk that is in those first squirts would be poor to test and would not have the needed results. This milk can either be thrown out or dumped down a drain. This step is also one that is used when doing a regular routine of milking cows. It is always important to take a few squirts out of each teat to make sure that the teat is opened up for the milk to flow out, along with making sure there are no objects in the way of the milk flow.

Step 4: Get Milk From Each Teat, Dump Into Paddle

The paddle will now come into use, you will milk out three to five squirts or until one section is half full of milk from all four quarters. It is not a big deal in which section of the paddle the milk is in. It also is not a big deal because if one quarter is full of mastitis, all the milk from the cow needs to be separated from the rest of the herds. Therefore all the milk will be mixed together from each quarter and will need to be disposed of.

Step 5: Add Reagant/ Mix Milk With Reagant

Next, take the bottle of California Mastitis Test reagent and put three drops or about that into each section of the paddle. It is important to not put too little of the reagent or too much. Too little or too much will make it so the test is inaccurate. Once there are three drops of the reagent in each quarter of the paddle swirl the paddle without spilling in either clockwise or counterclockwise circle for 15-20 seconds.

Step 6: Final Test

Finally, with the milk and the reagent mixed, now it is time to do the real test. With the latex gloves on, reach into the section of the paddle in which the milk is in, pinch the pointer and thumb fingers together and pull up the fingers out of the mixture while they are still pinched. The results are if the milk and reagent are thin and runny the test is negative, and the cow does not need to be further treated. If the milk is thick and stringy, the test is positive, the cow has mastitis and should be treated immediately, and milk can not go into the bulk tank.