Some bacteria that cause mastitis respond to common mastitis treatments and should be treated that way. However, evidence shows that many cases of clinical mastitis do not respond to antibiotic treatment and so should not be treated with antibiotics. How can someone know the difference?
The answer is by culturing the milk of clinically infected cows to at least categorize the pathogens as a type that responds or a type that does not. Many will say sending milk away for culture takes days and by then the cow should have been treated. That may be true, but dairy producers culturing their own milk is an alternative with a much shorter time until the results are known (see article “On-YOUR-farm milk culturing?”).
At least three dairy producers in northeast Michigan do their own on-farm milk cultures. All three of these producers consistently produce milk from cows with average bulk tank somatic cell counts (SCC) less than 100,000. Culturing milk is part of their complete program for cow health and quality milk, not only because it provides information for treating the cow with mastitis, but because it helps them monitor the herd udder health and fine-tune their prevention program.
Julie Nelkie and her daughter, Abigail O’Farrell, at Lemajru Dairy Farm, LLC of West Branch have been culturing milk samples for about 7 years. Charina Dellar of Dellar Dairy Farm in Harrisville got started almost two years ago and Keith Kartes of Circle K Farms in West Branch has been culturing milk for about a year now.
Even with a low average SCC, do these farms think it is worth it to culture clinical cows? “Yes” is how they all responded emphatically. In fact, they agree that culturing milk is a key to their maintaining low SCC.
Culturing milk provides greater information with which they can manage both the individual and the herd. In regard to the individual, it means that they make the decision often to not treat cows with clinical mastitis. Does the decision not to treat have risks?
Researchers have examined that question. Studies involving eight dairy herds in two states; Minnesota and Wisconsin, as well as Ontario, Canada, looked at the effect of treating all clinical cows or just treating cows likely to respond to antibiotic based on on-farm culturing. There were a total of 7,360 cows on these farms with 422 cases of mild or moderate mastitis during the study period.
Articles by Dr. Alfonso Lago et. al. detailing the results of this study and an associated one were published in the September 2011 issue of the Journal of Dairy Science (94:4441-4456). A second article details the impact of treatment decision on cow performance measures.