Pigs take a mud bath at the De Jofrahoeve pig farm in Esch, Netherlands. Dutch farmers treat their animals with almost three times the antibiotics that their Danish neighbors use. Robin Utrecht/AFP/Getty Images hide caption

itoggle caption Robin Utrecht/AFP/Getty Images

Breeding sows in crates at a subsidiary of Smithfield Foods in 2010. The photo was shot by the Humane Society as part of an undercover investigation. Humane Society/Associated Press hide caption

itoggle caption Humane Society/Associated Press

Many livestock groups say there's no evidence that antibiotics in livestock feed have caused a human health problem, but researchers beg to differ. Scott Olson/Getty Images hide caption

itoggle caption Scott Olson/Getty Images

Adrian Mesa protests the overuse of antibiotics in meat production outside a Burger King in Coral Gables, Fla. in 2003. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

Jennie Grant greets her goat Eloise in Seattle. No stranger to urban farming, Grant already had chickens, bees, and a large vegetable garden before she added goats to her lineup. Elaine Thompson/AP hide caption

itoggle caption Elaine Thompson/AP

A man with a cow in Dong Thap province in southern Vietnam. He got the cow from Heifer International — as well as training and resources to care for it. Courtesy of Juleen Lapporte hide caption

itoggle caption Courtesy of Juleen Lapporte

A truckload of live turkeys arrives at the Cargill plant in Springdale, Ark., on Aug. 4. Most turkeys in the U.S. are given low doses of antibiotics, which breed resistant strains of bacteria, including Salmonella. Danny Johnston/AP hide caption

itoggle caption Danny Johnston/AP