Milk tankload product for tankcars. Milk is a nutrient-rich, white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for infant mammals (including humans who are breastfed) before they are able to digest other types of food. It contains many other nutrients including protein and lactose. Interspecies consumption of milk is not uncommon, particularly among humans, many of whom consume the milk of other mammals. As an agricultural product, milk, also called dairy milk, is extracted from farm animals during or soon after pregnancy. Dairy farms produced about 730 million tonnes of milk in 2011, from 260 million dairy cows. Throughout the world, more than six billion people consume milk and milk products. Over 750 million people live in dairy farming households.