Chipotle restaurant workers fill orders for customers. The company is now sourcing some of its pork from a British supplier that uses antibiotics to treat pigs when ill. Gail Hansen, a veterinarian and longtime critic of antibiotic overuse on farms, welcomes this shift in Chipotle's stance on the drugs.
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Tyson Foods says it has already reduced its use of human-use antibiotics by 80 percent over the past four years. Here, Tyson frozen chicken on display at Piazza's market in Palo Alto, Calif., in 2010.
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.