Most of what we feed to chickens, pigs, and other farmed animals—most of it is burned off, simply keeping the animals alive until they're slaughtered.
It's bizarre, really: You take a crop like soybeans, oats, corn, or wheat, which are all high in protein, fiber, and complex carbohydrates but devoid of cholesterol and artery-clogging saturated fat. You feed them to an animal and create a product with no fiber or complex carbohydrates at all but with lots of cholesterol and saturated fat. It makes about as much sense as taking pure water, running it through a sewer system, and then drinking it.
Vegetarianism in a Nutshell: Environment