are birds. chickens and turkeys raised for meat live crowded by the thousands in warehouses while they grow to slaughter weight. the large number of birds makes a pecking order impossible, so fighting and cannibalism are common. for transport to slaughter, chickens are often roughly thrown into wire...
"chronic gastrointestinal diseases in dairy farmers in england and the welsh borders: is there an association between crohn's disease and bovine paratuberculosis?"...