Colostrum

Colostrum is the mammary secretion produced during the first four to five days after birth, the newborn’s first food and first medicine. It differs from mature milk above all in its high immunoglobulin content, which passively immunizes the suckling infant or animal while its own defences mature. It is also richer in milk fats, short-chain fatty acids, lactoferrin, minerals, and most vitamins, and it carries growth factors that help seal the newborn gut. Calves must receive it within hours of birth; the same urgency applies across mammals, including humans.