The FDA's latest effort to end the use of antibiotics as growth promoters in animals is getting mixed reviews from activists. Rob Carr/AP hide caption

itoggle caption Rob Carr/AP

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