The main purpose of animal production is to supply high-quality food for humans. Although animal products are not essential dietary components for humans other than the very young, meat, milk, cheese, and eggs are very satisfying to the palate and provide satiety. Moreover, animal proteins are of higher nutritional quality than plant proteins because they contain large amounts of essential amino acids required by man. Also, animal products supply vitamins, particularly B12, and valuable minerals. Livestock production is vital to man today and will be equally important in the future. The consumption of animal proteins by the affluent population of the U.S. is very high and provides almost 70% of the protein consumed, whereas the world population obtains only one third of its dietary protein from animal sources. The increasing world population and the rising standard of living will bring about an increased demand for animal proteins.