For related articles and more information, please visit OCA’s Mad Cow Disease page and our CAFO’s vs. Free Trade page.

Modern factory farms have so much wrong with them, but a starting point is the practice of turning pigs into cannibals.

A video, taken secretly by an undercover worker and scheduled to be released on Thursday by the Humane Society of the United States, pulls back the curtain on the banal brutality of a huge hog operation in Kentucky called Iron Maiden Farms (which declined to comment). The video shows barns filled with hogs jammed so tightly into tiny individual pens that they can’t move, chewing forlornly on the bars that restrain them.

It also shows workers gutting dead piglets and turning their intestines into a purée that is then fed back to the mother pigs, or sows. This is meant to immunize the sows against a virus, porcine epidemic diarrhea, or P.E.D., that has ravaged the hog industry, killing millions of piglets.

Tom Burkgren, the executive director of the American Association of Swine Veterinarians, said that feeding the piglet intestines to sows is legal and safe but that hog farmers are increasingly finding that it’s more effective simply to use diarrhea from an infected animal to expose sows to P.E.D.

“From a public health standpoint, I don’t think there’s a risk there,” Burkgren said, noting that P.E.D. affects only pigs. “There’s no mad pig disease.”

That’s a reference to mad cow disease, which was spread by feeding ground-up cows to other cows. Likewise, giant poultry farms feed “spent hen meal,” consisting of ground-up old chickens, to egg-laying hens.

Whether or not there are public health risks to feeding pig parts to pigs, there are larger issues about the way we raise our food. Nine out of 10 sows in America are kept in gestation crates, according to the National Pork Producers Council. These are tiny stalls that are barely bigger than the pigs, who don’t even have enough room to turn around.

They live out their adult lives without exercise or meaningful social interaction; it’s like a life sentence of solitary confinement in a coffin, punctuated by artificial insemination and birth. No wonder the animals’ muscles atrophy and they show signs of aggression and stress.