There are different systems of feeding cattle in animal husbandry. For pastured animals, grass is usually the forage that composes the majority of their diet. Cattle reared in feedlots are fed hay supplemented with grain, soy and other ingredients to increase the energy density of the feed. The debate is whether cattle should be raised on fodder primarily composed of grass or a concentrate. The issue is complicated by the political interests and confusion between labels such as "free range", "organic", or "natural". Cattle raised on a primarily foraged diet are termed grass-fed or pasture-raised; for example meat or milk may be called grass-fed beef or pasture-raised dairy. The term "pasture-raised" can lead to confusion with the term "free range", which does not describe exactly what the animals eat. Types of feeding Grazing Grazing by cattle is practiced in rangelands, pastures and grasslands. According to the Food and Agriculture Organization, about 60% of the world's grassland is occupied by grazing systems. "Grazing systems supply about 9 percent of the world's production of beef ... For an estimated 100 million people in arid areas, and probably a similar number in other zones, grazing livestock is the only possible source of livelihood." Integrated livestock-crop farming In this system, cattle are primarily fed on pastures, crop residues and fallows. Mixed farming systems are the largest category of livestock system in the world in terms of production. Lotfeeding and intensive finishing Lot feeding and intensive finishing are intensive forms of animal production. Cattle are often "finished" here, spending the last months before their slaughter gaining weight. They are fed nutritionally dense feed, also known as "concentrate", in stalls, pens and feedlots at high stocking densities in enclosures. This achieves maximal rates of liveweight gain. Types of cattle feeds Grass-fed Grass and other forage compose most or the majority of a grass-fed diet. There is debate whether cattle should be raised on diets primarily composed of pasture (grass) or on a concentrated diet of grain, soy, and other supplements. The issue is often complicated by the political interests and confusion between labels such as "free range", "organic", and "natural". Cattle reared on a primarily forage diet are termed grass-fed or pasture-raised; meat or milk may be called "grass-fed beef" or "pasture-raised dairy". The term "pasture-raised" can lead to confusion with the term "free range" which describes where the animals reside, but not what they eat.