Corn is what feeds the steer that becomes the steak. Corn feeds the chicken and the pig, the turkey and the lamb, the catfish and the tilapia and, increasingly, even the salmon, a
carnivore by nature that the fish farmers are reengineering to tolerate corn. The eggs are made of corn. The milk and cheese and yogurt, which once came from dairy cows that
grazed on grass, now typically come from cows that spend their working lives indoors tethered to machines, eating corn.
— The Omnivore's Dilemma: A Natural History of Four Meals
by Michael Pollan