Cows are very vulnerable to mastitis, a bacterial infection of the udder, in the first month after calving. Subclinical infections that have persisted through the dry period can flare into clinical cases, or cows can pick up new infections at calving or at milking.

The strategy for controlling mastitis depends on what bacteria is causing the problem in the fresh herd. There is only one way to establish this: collect milk samples from a number of affected cows and send them to a laboratory.

It is not possible to tell whether the first few cases at the start of calving are the only cows that are going to be affected, or whether the herd is on the verge of a sizeable clinical case problem.

So it is a good insurance policy to collect milk samples from all mastitis cases. These samples can be stored in the freezer and sent to a laboratory if a problem emerges in the next 3-4 weeks.

It is worthwhile talking with a vet about what the laboratory results mean and what to do next, especially if the herd has three clinical cases in less than 50 calvings.

It is also important to train the on-farm team about the importance of collecting good samples .  This gives the advising vet confidence in the results from the milk cultures, as well as reducing problems associated with “no growth” and “contamination”.

Samples are called “contaminated” when they yield a lot of different bacteria. The extra bacteria are usually introduced at sampling and may come from a fleck of (wet or dry) cow shit, from the outside surface of the teat skin, or even from the skin of the person collecting the sample!

“No growth” means that no bacteria grew at all. This can happen if the milk sample was collected after the cow was treated with antibiotic, or if the bacteria died during storage, handling or transport to the laboratory.

These results are frustrating because they take the same amount of time and money as other milk cultures but provide no information.

The Countdown Downunder Farm Guidelines for Mastitis Control provides a practical step-by-step guide for collecting milk samples. Some farms may find it worthwhile to get someone from outside the farm to train staff to ensure a good result.

Image and caption

“Milk samples can be taken, frozen and sent to a laboratory later, if you find a mastitis problem in the first few weeks after calving”

Countdown Downunder Farm Guideline or Technote
Farm Guideline 4.3, Fact Sheet A

Keywords
Calving, clinical cases, milk samples,

Word length
386