Here.

“Even ‘pasture-raised’ can be misleading. When I visited Joel Salatin’s farm in Virginia, I saw his ‘pasture-raised’ chickens, who were on pasture and also crowded into wire enclosures with low, corrugated metal roofs. They were overheating, some with open-mouth breathing. These chickens, like practically all chickens exploited for meat, were genetically bred to grow much faster than normal. The birds’ hearts and lungs have difficulty supporting such growth rates, and many die of heart attacks at just a few weeks old. The unventilated, cramped enclosures were not good for the welfare of these ‘pasture-raised’ birds.”