The antibody-rich first milk produced immediately before and after giving birth. The accumulated secretions of the mammary gland over the last few weeks of pregnancy. It is rich in IgG (65-90%) with variable levels of IgA and IgM. Form of passively acquired immunity (short-lived). Milk that is high in protective antibody and necessary for successful passive transfer. The milk secreted by female mammals for the first few days after birth. It is particularly rich in nutrients and antibodies essential for newborn survival. The first milk produced by the dam after giving birth. Colostrum is rich in antibodies.