Most animals require variety in their diet to achieve their best health. Goats, for example, have been shown to browse 470 of the 509 plants available in the testing region.
Sheep graze differently from cows. Chickens require more than just corn and laying mash. These nutritional requirements don't support a confinement feeding operation. Instead, nature is telling us how to best raise these animals in ways that benefit them and ultimately everyone who uses them for food.
Probably the most obvious problem with confinement feeding is waste management. The "droppings" of the animals become too concentrated for the confinement area. This results in odor, death to the soil micro-organisms and poor health for the confined animals. Conversely, the droppings of animals that are allowed sufficient acreage serve to fertilize the soil. They provide food for the micro-organisms that assimilate all nutrients back into the grass.