Milk is a biological liquid of a complex composition made of water, proteins, fats, carbohydrates, mineral mater, vitamins etc. The definition of milk, in the strictest sense of the word, implies the unaltered secretion of the mammary gland, obtained with the constant and complete milking of healthy, normally nourished, and regularly milked cows, at least 15 days before and 8 days after calving; nothing is to be taken or added to that milk.