Cattle in concentrated animal feeding operations (CAFOs) are typically fed corn, soy and other types of feed that can include "by-product feedstuff"^{[citation needed]}. As a high-starch, high-energy food, corn decreases the time to fatten cattle and increases yield from dairy cattle. These cattle are called corn-fed or grain-fed. In the United States, most grass fed cattle are raised for beef production. Dairy cattle are usually supplemented with grain to increase the efficiency of production and reduce the area needed to support the energy requirements of the herd. A growing number of health and environmental proponents in the United States such as the Union of Concerned Scientists advocate raising cattle on pasture and other forage. Complete adoption of farming practices like grass-fed beef production systems would dramatically increase the amount of land needed to raise beef