Antibiotics in Milk
Antibiotics are used on many farms to treat mastitis infections. Cows under antibiotic treatment for mastitis infections may have antibiotic residues in their milk, therefore, milk from treated cows is either discarded or collected into a separate tank. Milk containing antibiotic residues is not used for human consumption. The legal standard, as defined by the FDA, requires that milk contain no detectable antibiotics when analyzed using approved test methods (Grade A Pasteurized Milk Ordinance, 2007).
Every tank truck of milk in the US is tested for the presence of common antibiotic residues. Specifically, milk is pumped from the tank on the farm into a tanker trunk for delivery to the processing plant. The tank truck driver takes a sample each farm's milk before the milk is pumped into the truck. Before the milk can be unloaded at the processing plant, each load is tested for antibiotic residues. If the milk shows no evidence of antibiotics, it is pumped into the plant's holding tanks for further processing. If the milk does not pass antibiotic testing, the entire truck load of milk is discarded and the farm samples are tested to find the source of the antibiotic residues. Regulatory action is taken against the farm with the positive antibiotic test.