A pen at a feedlot in central Kansas that houses 30,000 cattle. Feedlots are where cattle are "finished" before slaughter, often with the use of growth-promoting drugs like zilpaterol.
Peggy Lowe/Harvest Public Media
Whenever a steer or cow leaves a farm in Michigan or goes to a slaughterhouse, it passes by a tag reader, and its ID number goes to a central computer that keeps track of every animal's location.
A security guard opens the gate at the Central Valley Meat Co., the California slaughterhouse recently shut down by federal regulators after they received a graphic video of cows being mistreated.