A Northwest cooperative tracked the incidences of antibiotic residues for two and one-half years and found 31 percent of the residue cases involved violations of the Pasteurized Milk Ordinance’s recommended procedures. This included extra label use of drugs, improper drug administration and failure to separate treated cows from the milking herd.

The study, conducted by field staff, included information on milk dumped at the farm as well as residues detected on the truck. The chart below shows the common reasons residues were found: