How Bovine Colostrum is Created
The formation of colostrum in the pregnant cow is initiated about 3-4 weeks before parturition when a limited amount of fluid containing small amounts of growth factors and other transforming substances is released into the developing mammary tissue. The process is regulated by a series of other hormones, one of the most important being progesterone, which attaches to special receptors on the cells lining the mammary gland and prevents them from secreting any fluid into the gland during most of pregnancy. About two weeks before birth, these substances influence the appearance of specific receptors on the surface of the cells lining the mammary gland that will facilitate the transfer of materials from the mother's blood into the gland, including the immunoglobulins (antibodies) necessary to convey passive immunity to the calf after birth and various hormones and growth promoters required to induce and support development of the newborn calf.
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 birth, one of the most influential factors on the composition of subsequent secretions is physical removal of the fluid from the mammary gland. The removal of even small quantities of fluid triggers the production of copious amounts of secretion from the cells in the mammary gland. Since the transfer of biologically-active substances from the mother's blood is blocked, replacement fluid will contain primarily substances synthesized by cells in the mammary gland and, thus, will be of a different composition than the fluid originally contained in the mammary gland at birth. The fluid expressed at this time is known as transitional milk. This is further complicated by the fact that the basic composition of the colostrum changes after birth due to maternal reabsorption and does so rapidly beginning at six hours, as can be seen from the table below.10 Thus, the highest quality bovine colostrum, containing the maximum concentration of biologically active substances, is collected in a single milking during the first six hours after parturition.
While the colostrum in the mother cow are changing quickly after the birth of the calf, the baby calf is undergoing a number of changes in its body. Within the first six hours of life, the calf's stomach lining does not produce any acid and there are a limited number of enzymes which break down proteins that are ingested.
Therefore, these conditions work in favor of having the biologically active substances in complete colostrum pass through the calf's stomachs into the upper portion of the small intestine without being broken down. During the first 6-8 hours of life, an area in the upper duodenum has specialized sites where the biologically active substances can be absorbed and transported directly into the calf's bloodstream. After this period, the stomach begins to acidify, enzymes appear and the specialized absorption area in the small intestine changes dramatically so that most of the biologically active substances in colostrum are no longer absorbed. This process is aided by the fact that calves are born with a well-developed system of lymphoid tissue under their tongue and at the back of their throat that persists throughout their entire life. Many biologically active substances are absorbed through these tissues when the calf suckles its mother or a nursing bottle. - 17269
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 birth, one of the most influential factors on the composition of subsequent secretions is physical removal of the fluid from the mammary gland. The removal of even small quantities of fluid triggers the production of copious amounts of secretion from the cells in the mammary gland. Since the transfer of biologically-active substances from the mother's blood is blocked, replacement fluid will contain primarily substances synthesized by cells in the mammary gland and, thus, will be of a different composition than the fluid originally contained in the mammary gland at birth. The fluid expressed at this time is known as transitional milk. This is further complicated by the fact that the basic composition of the colostrum changes after birth due to maternal reabsorption and does so rapidly beginning at six hours, as can be seen from the table below.10 Thus, the highest quality bovine colostrum, containing the maximum concentration of biologically active substances, is collected in a single milking during the first six hours after parturition.
While the colostrum in the mother cow are changing quickly after the birth of the calf, the baby calf is undergoing a number of changes in its body. Within the first six hours of life, the calf's stomach lining does not produce any acid and there are a limited number of enzymes which break down proteins that are ingested.
Therefore, these conditions work in favor of having the biologically active substances in complete colostrum pass through the calf's stomachs into the upper portion of the small intestine without being broken down. During the first 6-8 hours of life, an area in the upper duodenum has specialized sites where the biologically active substances can be absorbed and transported directly into the calf's bloodstream. After this period, the stomach begins to acidify, enzymes appear and the specialized absorption area in the small intestine changes dramatically so that most of the biologically active substances in colostrum are no longer absorbed. This process is aided by the fact that calves are born with a well-developed system of lymphoid tissue under their tongue and at the back of their throat that persists throughout their entire life. Many biologically active substances are absorbed through these tissues when the calf suckles its mother or a nursing bottle. - 17269
About the Author:
Dr. Kleinsmith is an expert in colostrum research. Learn more about the colostrum benefits by visiting the colostrum authorities online resources at ImmuneTree.com today!
posted by X - Men at
2:26 PM
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