Many states have diagnostic labs and they would have to be contacted regarding costs and shipping charges. Veterinary services also may conduct such tests. In Illinois, the price for a milk culture would be in the $3 to $5 range. Samples must be aseptic (no contamination) and frozen to assemble a group before shipping. See additional guidelines below from Dr. Dick Wallace (our Extension dairy veterinarian).
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
In Illinois, we prefer to sample cows that have elevated somatic cell counts (SCC). Look at the DHI records and select cows that have had over 300,000 SCC more than once in the last six months. Using the California Mastitis Test (CMT) paddle can help you identify the infected quarter or quarters. Sampling only the positive or high SCC quarters will improve your chances of detecting the offending bacteria.
Be careful in taking the samples. If you contaminate the milk samples, you might get the wrong impression of the types of bacteria involved in mastitis on the farm. Milk samples for bacterial culture must be obtained aseptically. They CANNOT be taken like DHI milk samples for fat, protein, SCC, and MUN (milk urea nitrogen). Prepare the udder for milking making sure you have taken a good fore strip of milk. Predip or wash the teats and thoroughly dry them with a paper or cloth towel. Scrub each teat end to be sampled with an alcohol pad. Scrub those teats on the far side first; when collecting samples, start with the teats on the closest side to avoid contamination by your hand or arm. Express a stream of milk, then catch 3 to 5 ml from the quarter in midstream. Seal the sample vial and refrigerate or place in a cooler right away. Send the milk samples to the lab as soon as possible. Samples may be frozen if necessary before delivery to the lab.
Dick Wallace, Dairy Extension Veterinarian, University of Illinois - Illini DairyNET
