"One time I visited a pig farm, a regular farm - not a factory farm - in Illinois. Right across the street was a hog CAFO. The owner didn't live there, of course. There's no farm house on a factory farm, just business offices. At night, all the workers would leave, and all I'd hear as I was trying to fall asleep was the sound of the pigs fighting each other, biting each other, squealing, screeching all night long. It was like nothing I've ever heard before in my life, and it just didn't stop. It sounded like kids being tortured over there. I'll never forget that sound. It was very sad." (
source)