And as modern farmers, they add, they must operate their large-scale hog farm to survive. In the past 10 years, big pork farms have sprung up across the United States. Since 1990, commercial pork production rose 26 percent while farm-raised pork dropped by half, USDA statistics show. Meanwhile, U.S. pork exports have quadrupled. Today most pigs are raised in 1,000-animal barns.
Food comes on a conveyor.
Waste falls through slats in concrete floors. Adult hogs are kept in pens, breeding sows in tight metal-barred crates. Nearby, pits hold lakes of watered-down manure. Bacteria break down some of the waste. The rest fertilizes cropland.