Fifty-four percent (1.2 billion acres) of land area in the 48 continental United States consists of grasslands, shrublands and open forests. For the most part, there is no alternative use of these land resources in production of food for man other than by way of ruminant animals. Sixty-nine percent (835 million acres) of these land resources is being utilized by grazing animals and forms the basis for a livestock industry which represents 43% of all agricultural receipts in the United States.
Smith, Edward M. and Turner, Larry W., "Energy in Agriculture: Grassland Renovation--Conserves Oil and Energy and Increases Returns from Grass Fields" (1978). Agricultural Engineering Energy Series. 23.