Antibiotics are chemicals that kill or impede bacterial cell growth. They are important medicines used by dairy farms to treat bovine bacterial infections, prevent infections, and to a declining degree to promote growth/milk production. When antibiotics are administered to dairy cattle, milk and meat withholding times are strictly followed to prevent antibiotic residues from entering the food system. Highly successful adherence to, and enforcement of, these regulations has resulted in only 0.01% of milk loads and 0.02% of dairy cattle slaughtered for beef testing positive for residues with protocols at processing plants preventing these products from entering the food chain.