<P> Animal feed is food given to domestic animals in the course of animal husbandry . There are two basic types, fodder and forage . Used alone, the word "feed" more often refers to fodder . </P> <P> "Fodder" refers particularly to foods or forages given to the animals (including plants cut and carried to them), rather than that which they forage for themselves . It includes hay, straw, silage, compressed and pelleted feeds, oils and mixed rations, and sprouted grains and legumes . Feed grains are the most important source of animal feed globally . The amount of grain used to produce the same unit of meat varies substantially . According to an estimate reported by the BBC in 2008, "Cows and sheep need 8kg of grain for every 1kg of meat they produce, pigs about 4kg . The most efficient poultry units need a mere 1.6 kg of feed to produce 1kg of chicken ." Farmed fish can also be fed on grain, and use even less than poultry . The two most important feed grains are maize and soyabean, and the United States is by far the largest exporter of both, averaging about half of the global maize trade and 40% of the global soya trade in the years leading up the 2012 drought . Other feed grains include wheat, oats, barley, and rice, among many others . </P> <P> Traditional sources of animal feed include household food scraps and the byproducts of food processing industries such as milling and brewing . Material remaining from milling oil crops like peanuts, soy, and corn are important sources of fodder . Scraps fed to pigs are called slop, and those fed to chicken are called chicken scratch . Brewer's spent grain is a byproduct of beer making that is widely used as animal feed . </P> <P> Compound feed is fodder that is blended from various raw materials and additives . These blends are formulated according to the specific requirements of the target animal . They are manufactured by feed compounders as meal type, pellets or crumbles . The main ingredients used in commercially prepared feed are the feed grains, which include corn, soybeans, sorghum, oats, and barley . </P>

What are two main components of cattle feed