News & Advice

Use milk samples as an insurance policy

Oct 3, 2018 | Dairy, Dairy Animal Health & Welfare, Milk Quality

John Penry, Veterinarian and Researcher, Anexa Vets

Every herd will experience clinical mastitis cases, particularly during the first third of lactation. They are obviously something we can do without, but even in herds with excellent environment and milking management, some level of clinical mastitis will be seen. When a cow is detected with a clinical case and treatment is started, some actions around administration are recommended in 100% of cases. One of those actions is cleaning and disinfection of the teat-end just prior to the lactating cow tube being inserted and the drug dose administered. This cleaning and disinfection step (with 70% meths or disinfectant teat wipes) significantly reduces the risk of a new bacteria being introduced into the quarter through the act of inserting the tube nozzle. 
Given this disinfection step is happening it makes sense to use this process for the maximum benefit and this is where the idea of taking a milk sample as “insurance” fits in. Once the teat end is disinfected, it only takes an additional minute to obtain a milk sample from the affected quarter immediately prior to inserting the treatment tube. This milk sample is not being used to guide treatment in this specific case, but rather to create a bank of milk samples that can be submitted for culture (bacteriology) should the new clinical case rate increase or pass the trigger point for action. If the farm does find that their clinical mastitis rate increases, knowledge of the dominant bacteria is pivotal in creating a prevention plan. While it is predicted that many cases will be Strep uberis, this should not be just assumed. Having a store of milk samples from clinical cases, representing the cases from say the previous six weeks buys you time and an advantage should an action plan be needed. 
So what are the specific steps required with these samples? Firstly, samples should be recorded with the cow ID, date and quarter. Secondly, samples should be frozen as soon as practical after milking – these frozen samples can be stored for three to four months without sample degradation. If, three months into the lactation, the clinical case rate is at an acceptable level, it is straightforward to throw out the first month of samples and just retain the last two months. Alternatively, if there is ample freezer space, samples can just be kept for the season and submitted based on sample age if the need arises. Even if you get to the end of the season and decide that no samples need to be submitted, by keeping frozen clinical mastitis samples all you have done is use up a little additional time at treatment insertion and used up a few tubes while maintaining an “insurance” for creating a mastitis action plan should the need arise. It is a great “belt and braces” approach to mitigating mastitis risk on any farm. 

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