Concerns about the health of livestock have also led the EU to pass some of the world’s strictest animal-welfare laws. Battery cages for egg-laying hens were banned in 2012, for instance. Legislative reforms have been harder to come by in America, especially at the federal level. Animal-welfare advocates lament the country’s congressional system, which gives disproportionate clout to rural states. Nevertheless, a rare but significant state-level change came last November when Californians voted to pass Proposition 12, which will ban the production and sale of pork, veal and eggs from animals kept in cages, bringing the state’s laws roughly in line with those in the EU. The change affects all meat producers who want to sell in America’s biggest state, putting pressure on them to change their farming practices. Public companies have been more responsive than lawmakers to animal-welfare concerns. Activists have achieved remarkable success in recent years by threatening companies with the release of unflattering images and videos of how their food is produced. Research by the Open Philanthropy Project, a group which funds animal-welfare activists, finds that such campaigns have prompted more than 200 American companies—including Mc- Donald’s, Burger King and Walmart—to stop buying eggs from chicken raised in battery cages since 2015. Farmers are therefore increasingly interested in improving the lives of their birds. Richard Swartzentruber owns two chicken sheds in Greenwood, a small town in Delaware. The company he supplies, Perdue Farms, has stopped using antibiotics altogether. Mr Swartzentruber’s chicken sheds have plenty of windows and doors that open onto a fenced grassy field whenever the weather permits. This comes with trade-offs: chickens might like perching on trees, but so do hawks. Inside the sheds, bales of hay, wooden boxes and plastic platforms are scattered around to entertain his chickens. Such measures have helped him gain a good-farming certificate from the Global Animal Partnership, a charity. Bruce Stewart-Brown, a food-safety scientist at Perdue Farms, says that his company would love to raise more organic chickens. His ability to provide higherwelfare organic meat is ultimately constrained by market forces, since the feed legally required is pricey. Although larger numbers of people might be willing to pay more for organic or free-range products, most still prefer whatever is cheapest. And, despite growing interest in vegetarianism and veganism, surveys find little evidence that many people in the rich world are turning into herbivores. People may like flirting with plant-based diets. But what they really love is chicken.