Milk

Milk, liquid secreted by the mammary glands of female mammals. It contains water, protein, fat, sugar, vitamins A, C, and D, and some B vitamins, as well as inorganic salts and minerals (calcium and phosphorus). In any species, milk serves as a complete food for the young of that species until weaning. Milk for human use is commercially produced by cows and water buffalo (especially in India); goat's milk is also commonly used in some areas, particularly the Middle East. An extremely perishable liquid, milk must be cooled to a temperature of not more than 10°C (50°F) within two hours of milking and maintained at that temperature until delivery.