Colostrogenesis: The Formation of Bovine Colostrum

A pregnant cow, about 3-4 weeks before delivery, creates what is called colostrum. It is created by a fluid which is released into the mammary tissue being developed in the mother cow. This fluid contains transforming substances and growth hormones such as progesterone. Progesterone attaches to the cell lining in the mammary gland and inhibits the cells from releasing any fluid into the gland during the pregnancy. These cells have receptors on them that help transfer substances such as antibodies, growth promoters and other hormones from the mother cow’s blood into the mammary gland. These substances help the calf in its development after it is born.

About 2 days before birth, the hormonal balance begins to shift, initiating the production of copious secretions and switching on the ability of cells in the mammary tissue to synthesize various substances, including lactose. At birth, when the placenta is eliminated, progesterone levels fall dramatically in the mother and its inhibitory control of the secretions is removed. Simultaneously, a protein-based substance develops in the cells lining the mammary gland that essentially blocks any further transfer of substances from the mother’s blood into the gland. The composition of the fluid in the mammary gland at birth is that of true colostrum and reflects the functional changes that have occurred in the gland up to that time; it a) has a high protein concentration, most of which is IgG; b) contains the highest concentration of growth promoters, other hormones and additional metabolically active substances; c) is low in lactose content; and d) is rich in milk fat.

After the mother cow delivers the calf, the removal of fluid from the mammary gland creates an abundant amount of secretion from the mammary gland. This replacement fluid is called transitional milk and will be different from the original fluid secreted from the mammary gland at birth. Another reason this replacement fluid is different from the original fluid is after birth the mother cow begins to reabsorb the fluid that is in the mammary gland. The highest quality of colostrum is collected in the first milking within six hours of the calf’s birth. The first milking contains the highest concentration of biologically active substances and nutrients. [I:http://www.2hourday.com/wp-content/uploads/2009/11/DrAnthonyKleinsmith0.gif]

The rapidly changing composition of colostrum in the mammary gland of the mother fits together very well with events that happen in the body of the newborn calf. During the first six hours of life, the calf’s stomach lining does not make any acid and there are very few, if any, enzymes present that can break down ingested proteins. Complete first milking colostrum also contains substances that inhibit the action of some enzymes.

In the first milking, the colostrum passes through the the stomach and the intestine of the calf without being broken down. Between 6-8 hours after birth, the calf begins to absorb and transport biologically active substances into the bloodstream. Then the stomach begins to acidify as well as enzymes begin to appear. The calf is born with lymphoid tissue that is well-developed which absorbs many biological active substances when the calf milks.

Dr. Anthony Kleinsmith is an expert in colostrum research. Learn more about the colostrum benefits by visiting his online resources at ImmuneTree.com today!