Young broilers nibble feed at a chicken farm in Luling, Texas. The Food and Drug Administration has issued new guidance on how drug companies label antibiotics for livestock. Bob Nichols/USDA/Flickr hide caption

itoggle caption Bob Nichols/USDA/Flickr

Turkeys sit in a barn in Sonoma, Calif. An estimated 46 million turkeys are cooked and eaten during Thanksgiving meals in the U.S. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

In recent years, pork producers have found ways to keep the animals healthy through improved hygiene. M. Spencer Green/AP hide caption

itoggle caption M. Spencer Green/AP

Beef cattle stand in a barn on the Larson Farms feedlot in Maple Park, Ill. Daniel Acker/Landov hide caption

itoggle caption Daniel Acker/Landov

Craig Rowles tends to his pigs in a barn near Carroll, Iowa. Dan Charles/NPR hide caption

itoggle caption Dan Charles/NPR