Antibiotic and antimicrobial are often used interchangeably. There is a difference, however.
Antibiotics are a class of pharmaceuticals which are substances produced by microbes.
Antimicrobials are essentially the same as antibiotics but also include substances of synthetic origin. Antimicrobials have been used in animal agriculture since the early 1950's to prevent and treat disease and improve feed efficiency. Antimicrobials serve an important role in reducing the incidence of infectious bacterial disease. The low-cost, plentiful and reliable source of meat, milk and eggs consumers enjoy is largely a result of the high health status of animals on Canadian farms. Antimicrobial resistance is the ability of certain bacteria, which are normally destroyed by a particular antimicrobial, to survive exposure to that antimicrobial.