On-farm Milk Culturing and Mastitis

Over the years, many methods of milk culturing have been employed to provide information regarding mastitis prevention, treatment, and control. In general, these efforts have centered on culturing in a laboratory located at a university, milk processor, or veterinary clinic. Products available on the market and efforts required to culture milk on the farm have, in general, been unsuccessful for various reasons. The main reason for frustration with on-farm milk culturing stems from the fact that it has been difficult to train, equip, and motivate farm personnel to ensure ongoing and accurate culturing for making treatment and prevention decisions. On the other hand, by the time culture results of clinical infections are reported back to the dairy for treatment decisions from off-farm laboratories, too much time has elapsed to be useful. This paper is intended to report on both success and failure in on-farm culturing, based on a methodology reported by Hess et al. (1). When confronted with an elevated herd somatic cell count (SCC) or an increased number of clinical mastitis cases, most managers of dairy herds are quite knowledgeable about effective measures for controlling and dealing with these problems. It is not so much an issue of lack of knowledge as it is a lack of attention to the details of implementation that make the real difference in the production of quality milk. It is simply a matter of milking clean, dry, and comfortable cows with properly functioning milking equipment. Mastitis researcher J. Woodrow Pankey was fond of saying that “there are only four ways that a cow gets mastitis: left front, right front, left rear, right rear!” The trick is to ensure that the bacteria on the outside do not become the bacteria on the inside. There are many strategies for doing this, but they all boil down to two basic tenets: decrease the exposure to bacterial pathogens and increase the resistance of the cow to these infections. Despite all of our advances in both strategies, cows continue to develop intramammary infections, and will for the foreseeable future. The ability to identify these bacteria allows the producer and his employees to devise both prevention and treatment plans to deal with the reality of clinical mastitis. Bacteria that are commonly associated with mastitis in dairy cows are most commonly categorized by the type of stain that they take in the laboratory. The most commonly employed stain is the Gram stain, and it has two possible outcomes. Gram-positive bacterial cells will have a purple or blue color when observed under the microscope. Streptococcus and Staphylococcus organisms are common Gram-positive bacteria. Gram-negative mastitis causing organisms, such as E. coli, Aerobacter, and Klebsiella, have cells that stain with a red color when observed under the microscope. On-farm Milk Culturing and Mastitis http://www.mdr.msu.edu Michigan Dairy Review