Final answer:
Breast milk composition changes during lactation and a single feeding. Colostrum provides immune defenses and mature milk changes from foremilk to hindmilk.
Step-by-step explanation:
The composition of breast milk changes during the first days of lactation and in the course of a single feeding. Colostrum, the milk produced in the first postpartum days, provides immunoglobulins that increase the newborn's immune defenses. Transitional milk and mature breast milk are ideally suited to each stage of the newborn's development, and breastfeeding helps the newborn's digestive system expel meconium and clear bilirubin. Mature milk changes from the beginning to the end of a feeding. Foremilk quenches the infant's thirst, whereas hindmilk satisfies the infant's appetite.