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Getting the most from CMT (California mastitis test)

I have begun a lot of training around mastitis control using my #udderthings program. One tool that is very useful when we are managing subclinical mastitis is the CMT test.

In the short video below, I outline some of the things I think are important when using it.

With cell count issues, we need to identify infected cows and quarters. We must then decide what action to take around each case based on their history.

Milk recording is an absolute must when it comes to dairy farming, with a push towards selective dry cow therapy in the coming years. Every dairy farm will need to be considering milk recording.

These records are invaluable for several reasons.

They are particularly useful when managing cell count and decision making; couple this with using your CMT test, we can make excellent decisions around milk quality and cell count.


CMT testing

This test identifies quarters with a cell count of over 400,000 cells per ml. It does this by causing a gelling reaction with the white blood cells (somatic cells) and the reagent.

The level of gelling reaction will be in relation to how high the somatic cells are. With a very high quarter, you can get quite a lot of thickening. These can be scored from 1-3, with a score of three being a lot of gelling (almost gloopy).

The more we use this test, the more accurate we are at picking up this gelling reaction.

We can also choose to sample these cases to check what pathogens are involved. Remember these samples can be frozen and sent off in batches. This is particularly useful as you approach drying off to make decisions around the dry cow antibiotic selection.

It takes a little practice and consistent routine, but CMT can prove to be a valuable tool.

At the beginning of lactation, we can CMT existing high cows to check for effective treatments during the dry period. We can also use it to review any cows going into the tank for the first time.

Where it’s worth, its weight in gold is monitoring high cell count cows in conjunction with milk records. It can also be used to significant effect to review treatment success in infected quarters.

Testing feeds into better decisions around individual quarters, where we may have to decide treatment worthiness and to make decisions around drying off quarters.

Like any other cow-side test, it is just a tool in the arsenal in mastitis control.

There are also some digital tools now on the market which measure conductivity and cell count. Again, once they are working well, they provide help in one of the critical elements in mastitis SCC control. This is the identification of problem cows and quarters.

Once we take action when we identify these, we can look at other risk factors and focus on reducing the spread of infection.

All decisions should be made in conjunction with your vet and milk advisor.


New project

I’ve been fortunate to become involved with two farms that want to dig deep into animal health over the next 12 months.

I’m taking them on to run some trials, test out farm health programs and training with staff. One of the areas for one farm is cell count, so hopefully, I will get to upload some updates from the farms as we go through the process. They also have kindly agreed to double up as my film studio!!!

We have a couple of clear challenges on one farm. This farm has been recently taken over, and they want to build a solid animal health base over the next 12 months.

Cell count in this herd is running at 300k, and with new management, we have set an ambitious goal to have this under 100k in 12 months. This will not be done by culling alone as the herd is also now expanding. It will test me and my udderthings program out, I feel.

Back out training

Its been great for the last month to get back out on-farm training staff and team members. It struck me last week working with one of those teams the caliber of people working on Irish farms. We often don’t give them or should I say they don’t give themselves enough credit for their abilities, energy, and enthusiasm. I love people development and enjoy the challenge and level of questions I get in my workshops.

One wish I have is if we are to continue to attract people into farming. Showcase the exciting opportunities to work in a growing and evolving businesses. We need to set the right tone.

A bugbear of mine for some time has been the use of the term labour units.

What other business would use this term for people? If we are to evolve, grow, and create the right environments to attract new people to farming. We need to start referring to them as people, not labour units.

I’ve banned this word from my own vocabulary when working with farming teams, as an industry is it time to do the same. It might seem pedantic but in my opinion our language and vocabulary can set a tone!

Just a thought


Happy, safe farming





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