Livestock grazing is one of the most widespread and important uses of rangelands. Renewable plant resources provide forage for ruminant livestock like cattle, sheep, and goats; and the ruminant animals subsequently provide food and fiber for people. This method of harvesting solar energy requires relatively low inputs of petroleum products for agricultural production. Rangeland livestock, however, must be managed properly to ensure the long-term sustainability of the soil-plant-animal resource base.