Differences between sows’ colostrum, transitional and mature milk

During gestation and around the time of delivery, the mammary gland undergoes structural and functional changes that prepare the organ for milk synthesis and secretion.

The endocrine environment of pregnancy initiates and drives structural changes in the gland and the progressive differentiation of milk-producing lactocytes.

Lactocyte-secreting differentiation encompasses the first stage of lactogenesis and results in the accumulation of colostrum in the gland.

This first stage of lactogenesis is characterized by low levels of milk protein and lactose synthesis. While there is an active transport of immunoglobulin G (IgG) molecules through lactocytes.

Colostrum is available to newborns immediately after birth. The high energy and IgG content of colostrum is particularly important in  pigs, as piglets tend to have scarce body fat reserves, have no circulating antibodies, and lack a fully functional immune system.

Therefore, newborn piglets depend on colostrum intake for thermogenesis and the establishment of passive immunity.

The second phase of lactogenesis begins 24 to 36 h after delivery and is characterized by secretory activation of lactocytes.