Video: Innovations on an Organic Dairy -- California Mastitis Test

eOrganic authors:

Kevin Jahnke, Jahnke Family Farm

Harriet Behar, Midwest Organic and Sustainable Education Service (MOSES)

Amanda Gervais, University of Vermont Extension


Mastitis, the medical term for inflammation of the udder, is the number one disease problem in dairy farming throughout the world. Typically, mastitis is classified into two major groups: a) environmental mastitis (caused when cows come into contact with a contaminated environment) and b) contagious mastitis (caused by bacteria on the teat and/or inside the udder). Contagious mastitits is often further divided into three groups: 1) clinical, 2) sub-clinical, and 3) chronic mastitis.

Clinical mastitis are those infections that are typically accompanied by the classic signs of inflammation including redness, swelling, pain, and abnormal milk. Subclinical and chronic mastitis, however, are infections where there are high somatic cell counts but the udder and milk may appear normal. In these cases, mastitis can only be detected with methods that measure the number of somatic cells in milk. One low-cost, easy way to detect subclinical or chronic masitits is the California Mastitis Test (CMT). The CMT is a screening test that indicates when the somatic cell count (SCC) is higher than 300,000.

In this video, filmed by Harriet Behar of the Midwest Organic and Sustainable Education Service (MOSES), Wisconsin organic dairy farmer Kevin Jahnke describes how he uses the California Masistitis Test (CMT) and other strategies to maintain high quality milk. 

Watch the video clip at

Audio Text

Hi, my name is Kevin Jahnke. I farm with my wife, Mary, and my three boys on Jahnke Family Farm. I’m the fourth generation farmer on our farm. It’s a seasonal, grass-based dairy. We milk 50 cows. We’ve been milking here for about eight years. We started on an Organic Valley truck right away, and we’ve focused mainly on a grass-based system and producing high quality milk.

We use a CMT paddle to monitor the cows and hold out the high milk, and consistently produce high quality milk. I’m going to show you the CMT paddles that we use. The CMT paddle stands for California Mastitis Test. It consists of a simple paddle that you squirt milk from each quarter into, and then there’s a solution that you add to the milk in equal parts, a one-to-one ratio. The solution from the CMT reacts with the white blood cells in the milk, so when there’s a high somatic cell count in the milk, it will react and the milk will gel up. What you look for, in a good, clean cow, the viscosity is going to stay the same as the milk. The thicker it gets, the higher the cell count is going to be.

So what we do is, we screen every cow that comes fresh. We screen her, look for anybody with a high quarter and we hold that quarter out. And that milk goes to the calves. We use a quarter milker to isolate that milk. We also have a second pipeline installed in our barn for a cow that is high in more than one quarter, so we isolate all of that milk to go to the calves as well.

This is a quarter milker. This is what you can use to isolate the high quarter from an identified cow. So what the quarter milker does is normally you have a milking claw where the milk goes in the four quarters. With the quarter milker, you can actually take the milk from your high quarter, separate it from the other three quarters, and capture it in this bucket. It uses the same vacuum as the claw vacuum. It’s pretty handy to use, and for the price that you invest in the quarter milker, it more than pays for itself in the high milk you take out of the tank in milk premiums, so it’s win-win situation for everybody. It’s a really good tool to lower your bulk tank score to hold that high milk out.

On our farm, I’ve installed a second pipeline to isolate my high somatic cell milk. I’ve come up with a device to utilize that second pipeline. A simple thing here has become a quarter milker. I can hook this up to the second pipeline, take my milker unit, and hook the inflation up to the second hose. Right now, when I hook this up to the cow, the milk from this quarter is going up this hose into my second pipeline into the milk that I’ve isolated for calf milk.

What we’re going to do is prep these cows and I’ll do a CMT on them. A CMT paddle, in my opinion, is the absolutely best management tool that a farmer can have. You’ll get the milk to the outside ring and add equal amounts of the solution, and then you just swirl it around and look for the one that gels up. This one is obviously gelled up.

A high cell count milk can be used to feed the calves. With the second pipeline, it goes into the other room. I’ve got a plate cooler that I use as a pasteurizer or to warm up the milk. The milk falls into the barrel and I heat it up; I’ve got a water line from here to the calf building that pumps it over there. I can feed all of my calves with this system that I’ve got set up, I never even physically handle the milk—it’s pumped from here over there, it gets warmed up and it is fed to the calves and I never touch it. As far as a good labor-based system, you can’t beat it.

Healthy cows don’t fluctuate much in cell counts. When cows are under stress, when their nutrition changes dramatically, when their environment changes, that’s when the cell count really fluctuates. But if you can focus on feeding the cows right, keeping them stress-free, clean, and good udder prep with good practices, your cell counts generally are going to stay really consistent.

[Harriet Behar, MOSES: What do you average?]

Last year, we averaged about 60,000 for the year. Probably this year we might be able to be a little bit lower because we sold off a lot of our nurse cows last year so now we’re holding out some cows; some of these cows’ milk I’m feeding to the calves only have a cell count of 2 or 300,000 but they’re the highest ones I’ve got so that whose feeding the calves.

A lot of people ask me what’s the secret to having a low cell count and I don’t think there is one thing. We all are good farmers or we wouldn’t be here but there are just a lot of little things that I’ve been fortunate to be on enough farms to pick up all the good things that everybody does and be able to use them for my advantage.

Additional Resources


Published May 2, 2012

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.