Antibiotics are used more heavily in farm animals than in people. This may be the largest source of antibiotic-resistant bacteria. Drug-resistance genes spread more widely and rapidly on farms than scientists ever thought, new discoveries show. The agriculture industry says fears are exaggerated, whereas researchers say companies are endangering public health. It wasn’t until a pig nosed me in the backside, in a friendly way, that I mustered the courage to touch one. I had seen thousands of hogs over the past 18 hours, but I had been nervously keeping my hands to myself. This particular pig seemed to disapprove of my restraint. I scratched him on the crown of his pink, wiry-haired head. He snorted loudly.