Milk has featured frequently in mythology and legend down through the ages. The fledging dairy industry it spawned spread across the world in the train of the European diaspora. In modern times, factors contributing to the growth of the dairy industry include technological innovation in the preservation of milk quality and in dairy product manufacture as well as improvements in breeding and rearing of dairy cattle for milk production. Mammals are warm-blooded vertebrate animals that nourish their young with milk produced by mammary glands. Milk, being the sole source of nourishment for the neonate, contains all the essential nutrients required for growth and development. Milk proteins can be readily separated into casein and whey protein fractions. Curd may be formed by the agglomeration of casein micelles following enzyme treatment in cheese manufacture. The fat globules of milk are enveloped in a layer of surface active material, which is called the milk fat globule membrane.