Final answer:
Colostrum is the first mammary secretion in late pregnancy, containing high protein levels but less fat and glucose than mature breast milk. It provides essential nutrients to the newborn, aligning with the biology of lactation stimulated by suckling.
Step-by-step explanation:
The mammary secretion that occurs in late pregnancy, which is similar to breast milk but contains less fat, is called colostrum. During the final weeks of pregnancy, the alveoli in the mammary glands swell with this substance. Colostrum is a thick, yellowish fluid that is high in protein but contains less fat and glucose in comparison to mature breast milk. It plays a crucial role in providing necessary nutrients and antibodies to the newborn, preparing them for digestion of breast milk, and offering protection against infections. After childbirth, colostrum is followed by transitional milk and then by mature milk, which usually begins to be secreted around the tenth postpartum day.
Lactation is the process which involves the synthesis and secretion of milk by the mammary glands, and it is stimulated by the hormones prolactin and oxytocin, which are released when the baby suckles at the breast.