The two are not mutually exclusive; each carries a significant tax on the animal's health and immune system.
Humans are fairly unique in our dietary flexibility; most other animals are evolutionarily adapted to a narrow range of foods. Corn provides caloric energy, but little more; a cow needs to eat grass, and move around, in order to be healthy.
Humans are fairly unique in our dietary flexibility; most other animals are evolutionarily adapted to a narrow range of foods. Corn provides caloric energy, but little more; a cow needs to eat grass, and move around, in order to be healthy.