""When a cow is slaughtered, about half of it by weight is not eaten by humans: the intestines and their contents, the head, hooves, and horns, as well as bones and blood. These are dumped into giant grinders at rendering plants, as are the entire bodies of cows and other farm animals known to be diseased. Rendering is a $2.4 billion-a-year industry, processing forty billion pounds of dead animals a year. There is simply no such thing in America as an animal too ravaged by disease, too cancerous, or too putrid to be welcomed by the embracing arms of the renderer. Another staple of the renderer's diet, in addition to farm animals, is euthanized pets, the six or seven million dogs and cats that are killed in animal shelters every year. The city of Los Angeles alone, for example, sends some two hundred tons of euthanized cats and dogs to a rendering plant every month. Added to the blend are the euthanized catch of animal control agencies, and roadkill. (Roadkill is not collected daily, and in the summer, the better roadkill collection crews can generally smell it before they can see it.) When the gruesome mix is ground and steam-cooked, the lighter, fatty material floating to the top gets refined for use in such products as cosmetics, lubricants, soaps, candles, and waxes. The heavier protein material is dried and pulverized into a brown powder, about a quarter of which consists of fecal material. The powder is used as an additive to almost all pet food as well as to livestock feed. Farmers call it protein concentrates. In 1995, five million tons of processed slaughterhouse leftovers were sold for animal feed in the United States. I used to feed tons of the stuff to my own livestock. It never concerned me that I was feeding cattle to cattle."
~~ Howard Lyman, 'Mad Cowboy'