How do mammal mother’s milk and lactation support newborns?

All mammals feed their young with milk produced by mammary glands, which is where the group gets its name. Milk is more than food: it contains fats, proteins, sugars, immune factors, and minerals suited to the baby’s needs. In the earliest days of life, this can be crucial because newborns often have immature immune systems. Different mammals produce milk with different compositions depending on growth rate and habitat. Lactation is a major evolutionary success that helps mammal young survive during their most vulnerable stage.