Different cattle feeding production systems have separate advantages and disadvantages. Most cattle in the US have a diet that is composed of at least some forage (grass, legumes, or silage). In fact, most beef cattle are raised on pasture from birth in the spring until autumn (7 to 9 months). Then for pasture-fed animals, grass is the forage that composes all or at least the great majority of their diet. Cattle fattened in feedlots are fed small amounts of hay supplemented with grain, soy and other ingredients in order to increase the energy density of the diet.