Antibiotics are used on dairy farms to treat mastitis infections. There are two types of Mastitis, infectious and non-infectious. Mastitis is an infection in the utter (mammary gland) of a cow. Cows under antibiotic treatment for mastitis can have antibiotic residue in their milk. According to the Grade A Pasteurized Milk Ordinance of 2007, milk from dairy cows receiving antibiotics for any reason is either discarded or collected into a separate tank. The FDA requires that milk contain no measurable amounts of antibiotics when analyzed using approved testing methods.
Every tanker truck of milk in the United States is tested for the presence of antibiotic residue before being introduced to the production line. Milk is taken from the cows on a dairy farm by a trunk to the processing plant. The driver tests a sample of each farm’s milk before the milk is pumped into the truck. As a safe guard, milk cannot be unloaded at the processing plant, until each load is tested again for antibiotics. If the milk does not pass antibiotic testing, the entire truck load of milk must be discarded. All of the farm samples are re-tested to find the source of the antibiotic residue. Any farmer that is found with antibiotics in their milk is subject to regulatory action.