TB Testing

I am by no means an expert on TB in cows so let me just start there. What I do know is the process we face and what it means for us as a farm.

Our farm is in an area that is tested for TB every six months. We lost several cattle and where closed down with TB over a period last year so the tests are always a nerve racking time- nobody gets much sleep on the run up to the test or waiting for the results day.

(Just a heads up- I am no vet and to be honest I don’t know much about the science behind the whole thing. I just know how it effects us and what we have to do, so if you are after an extensive read on TB I would try a more specific website, but if you just wonder what goes on across the average farm then this is perfect!)

The vet comes to visit the farm and all of our cattle including calfs have to be tested. The vet will do two visits- one to inject the animals and a second to read the results and declare TB or no TB!

So our vet comes on a Tuesday, Monday is spent preparing. Ad we have a lot of cattle to get through we will often spend the afternoon prior to the test setting up pens and races that allows us to easily manage the cattle on the day and make the whole process as stress free as possible.

On the first visit the cattle are moved through the series of pens or races and run into the crush. The word ‘the crush’ sounds horrible but it’s just the terminology. The crush is a pen that has bars all around it (pictured below), the main reason for this is safety. Cows are big strong animals and if they decide to kick out and flat up when injected they could easily injure those involved. The crush limits their ability to move around and makes it safe to handle the cow. By opening the gate on the front of the crush the animal will freely walk in, you then close the gate and they are confined, the test is done and the gate is opened to release them.

The vet injects every cow twice in the skin on their neck- the injection is two different forms of tuberculin. Once complete the vet then returns three days later so for us the Friday to see the results. The same process takes place with the cows all coming out into the yard and through the crush but this time the vet is looking for reactions to the injection.

The vet will read the cow number and then measure any reactions that have taken place.  they are looking for lumps where the skin has swelled around the injection. There can be three out comes from the testing:

  1. If no reaction or a reactive lump is below a certain size that cattle is deemed clear and we move onto the next
  2. If there is a lump but the reaction is different to that expected- the one injection reaction is bigger than the other (without getting technical it’s easier to think of it in this way) you get an in-conclusive result. In this instance the cattle and farm are put under restrictions but re-testing is done to give a pass or fail result.
  3. If the lump shows above a certain size when measured the cow is classed as having TB and the farm is shut down.

Result 3 is clearly the worst result any farmer would face. The cattle that tested positive have to be taken for slaughter and it can be devastating, especially if it’s a pregnant cow or a young calf. The farm is then put under restrictive movement regulations meaning you cannot sell or buy any cattle until you are clear. Under the restrictions the farm will then move onto 3 monthly testing and until you get two consecutive clear results of TB the restrictions remain in place.

The reason this can be so devastating for farms is the time period it can last- so to give you an example scenario. You test positive and loose 5 cows that day, for 3 months you cannot get any income from selling any cattle so your cash flow is affected. At the next test you have another 5 cows test positive and sent for slaughter. Another 3 months goes past but this time you test clear, you then face another 3 months until a second clear result where you are released from restrictions. In total 10 cows have gone to slaughter, and a period of 9 months have passed where no income can be generated from the cattle. this is just a short example, for some farmers it can go over a period of years and can sometimes lead to the fold of small farms.


Luckily for us we were clear, so everyone can rest easy for six months until the next test!

I managed to capture a small amount of the testing taking place in the video below. It’s not the best quality as its a very stressful test and more focus is on managing the cows and the test than the video for obvious reasons, but hopefully it gives you a little insight into the process.



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