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Culturing milk useful for fighting mastitis

January 24, 2020

Emily Wilmes, University of Minnesota Extension

It’s only way to 100% diagnose infectious mastitis

Fighting mastitis on your dairy can be a difficult task. For one cow, a treatment will work great and she’s back to normal in a short amount of time. For another cow, that same treatment may have little to no success, and you’re left scratching your head about what to do next to help this cow. This would be the perfect time for you to start doing milk sample bacterial cultures on your cows. Why is this helpful? Well it’s only way to 100% diagnose infectious mastitis, but–more importantly–it identifies the causative organism.

Back to our cow we can’t clear up the infection on: it’s possible her mastitis was caused by a different pathogen than her herdmate’s was. The mastitis tube you treated the first cow with may not be effective against the pathogen the second cow has.

Milk culturing can be done through the DHIA, and other laboratories. Collecting a sample is easy to do and doesn’t take a lot of extra time; simply milk the sample from a clean, dry teat into a clean and dry tube. After you have collected the sample, keep it cold until it can be picked up or delivered.

If you aren’t convinced individual cow culturing is for you, then you can try doing a bulk tank culture. Bulk tank culturing is still a useful tool because it can help determine the general types of bacteria present in cows within a herd, as well as the amount of exposure to environmental bacteria. Bulk tank culturing is a rapid, inexpensive way to determine some types of information when trying to troubleshoot problems in the dairy herd or for monitoring exposure.

When collecting a bulk tank sample to send in, you will want to take a sample five days in a row. This will improve the accuracy of your test result. Each of the five days, agitate the tank 5-10 minutes before sampling. Be sure you use a clean dipper and don’t be afraid to ask your milk truck driver if you have any questions about the procedure, as they have lots of experience taking tank samples. Since you are taking 5 days’ worth of samples, you will want to freeze each sample to discourage bacteria growth. Milk expands when it freezes, so only fill the sample tube about ? full. If you need to ship the samples yourself, make sure they are packed in a way that will keep them frozen. Labs can only test samples that arrive frozen or cold.

Doing a milk sample bacterial culture of your individual cows or even your bulk tank will help you determine what pathogens you are fighting as well as the environmental exposure of your herd. Bulk tank samples especially are very economical, but you will find individual samples can be cost effective as well, as you won’t be wasting time or money on mastitis tubes that won’t work.



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