Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all post-pregnancy female mammals, although it predates mammals.[1] In humans the process of feeding milk is also called breastfeeding or nursing. Newborn infants often produce some milk from their own breast tissue, known colloquially as witch's milk.
In most species, milk comes out of the mother's nipples; however, the monotremes, egg-laying mammals, lack nipples and release milk through ducts in the abdomen. In only one species of mammal, the Dayak fruit bat from Southeast Asia, is milk production a normal male function.