The Ross 308 is the top-selling chicken breed worldwide, common to the point of ubiquity. The 308 and its close relatives account for about two-fifths of the 22.7 billion chickens being raised for meat on the planet on any given day. Most spend their brief lives indoors in cramped conditions suffering injury and illness, unable to engage in natural behaviors.

Behind the 308 lie a host of animal welfare concerns that have largely been ignored. Over the decades, its progenitors have been selectively bred to dramatically reduce costs for producers. These days, they reach slaughter weight three times faster than chickens in the 1950s. But according to numerous peer-reviewed studies and European government reports, that breeding has led to an array of health issues: Leg and skeletal defects appeared first, causing painful lameness and the premature death of bone cells. These were followed by cardiovascular problems that made mortality rates spike. More recently, researchers have encountered muscle abnormalities with oddball names like woody breast syndrome (pale areas where the flesh has hardened) and spaghetti meat (fibers separating into stringlike bundles).