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|Collection and preparation of milk samples for microbiological culturing|
|Dairy basics - Herd Health|
|Written by Jeffrey M. Bewley|
In developing individual farm mastitis control and treatment strategies, it is often necessary to characterize the types of bacteria that are present on your farm. To answer this question, a microbiological analysis, or milk culture, must be performed on milk samples collected from cows showing clinical or subclinical signs of mastitis. Results of the milk cultures will help identify which bacteria are causing the mastitis.
In turn, this information can be used to alter mastitis control, prevention, and treatment options to fit your herd’s conditions. During an investigation of a herd dealing with high somatic cell counts or a high incidence of clinical mastitis, milk culture results provide essential evidence for solving the problem.
When managing a contagious mastitis problem (Staphylococcus aureus or Streptococcus agalactiae), milk cultures are even more important to help make individual cow treatment and culling decisions.
Extra care and precaution are necessary during the collection process, using strict, clean, aseptic (without germs and bacteria) procedures to be sure that the bacteria originated from milk from the udder and not the teat end or hair, the sampler’s hands, or the barn environment.
If the samples are not collected, handled, and transported correctly, the bacteriological results will be of no diagnostic value.
Alcohol-soaked cotton balls or gauze pads should be used to sanitize the teat ends. If a large number of samples are being collected, a rack may be needed to handle sample vials.
If the entire herd is being sampled, composite samples (all four quarters in one collection vial) will provide reasonable results. To minimize contamination and maximize the chances of receiving useful information from the milk culturing process, adhere to guidelines for the aseptic collection of clean milk samples. PD