Sources of potential residue problems in dairy herds.

Drugs and chemicals provide economic benefit to animal and crop production; to derive this benefit they must be used appropriately. Data from the United States Department of Agriculture, Food Safety and Quality Service residue monitoring program indicates certain drugs and chemicals are not being used appropriately by the dairy industry, and residues are occurring in cow carcasses at slaughter. Residues of antibiotics and certain pesticides which are administered intentionally are being found. Dairy cows are also particularly susceptible to inadvertant exposure to chemicals because of certain management practices and physiologic characteristics of dairy cows. Contamination of Michigan dairy cows with polybrominated biphenyls is an example. Methods of controlling both intentional and unintentional exposure of cows to drugs and chemicals will require considerable involvement of producers.