Some antibiotics are approved for use in animals, others in people, and still others in both animals and people (also called shared class antibiotics), but the majority of antibiotics used in animals are non-critical to human medicine.
Animal welfare, food safety and sustainability – there are good reasons animals raised for food are given antibiotics. Responsible use of antibiotics is the key, and procedures are in place to ensure there are no unsafe residues in meat, milk and eggs.
The term “factory farm” (I call it the “double F bomb”) has become a catch-all for everything that some people perceive as being wrong with modern agriculture. A recent New York Times op-ed contains much misinformation about today’s farming technology, the healthfulness of meat, and the environmental impact of producing food from animals.