river 625 miles (1006 kilometers) Canada & United States in Alberta & Montana flowing SE into Missouri River
Liquid secreted by the mammary glands of female mammals to nourish their young. The milk of domesticated animals is also an important food source for humans. Most milk consumed in Western countries is from cows; other important sources include sheep, goats, water buffalo, and camels. Milk is essentially an emulsion of fat and protein in water, along with dissolved sugar, minerals (including calcium and phosphorus), and vitamins, particularly vitamin B complex. Commercially processed cow's milk is commonly enriched with vitamins A and D. Many countries require pasteurization to protect against naturally occurring and artificially introduced microorganisms. Cooling further prevents spoilage (souring and curdling). Fat from whole milk (about 3.5% fat content) can be removed in a separator to produce cream and leave low-fat milk (1–2% fat) or skim milk (0.5% fat). Milk is usually homogenized, forced under high pressure through small openings to distribute the fat evenly. It may also be condensed, evaporated, or dehydrated for preservation and ease of transport. Other dairy products include butter, cheese, and yogurt.