Because pigs will eat almost anything, they have traditionally been fed farm leftovers and waste. This unappealing diet commonly known as slop may contain food waste from a farm household or the unusable by-products of the manufacturing processes for things like butter and cheese and even beer brewing. Pigs are natural foragers, frequently using their snouts to dig up roots or grubs for food when they are in the wild. On farms they are fed from low troughs, but their big snouts and foraging habits still make them very messy eaters. Adding to the dirty reputation of pigs is the fact that they have usually been kept in pens, or sties, close to farm buildings to make their feeding quick and easy. They and their messes have been confined to small spaces, unlike cows and sheep, which are free to roam pastureland. Because pigs are raised mainly for their meat and fat, they are given a lot of food and spend most of their time eating. Piglets that weigh only a few pounds at birth can reach more than 200 pounds (90 kilograms) in less than half a year.