| Popis: |
Immunoglobulins (Igs) in milk and colostrum give the offspring an immunological protection against microbial and viral pathogens and toxins and protect the mammary gland against infections. Colostrum, in particular, is rich in Igs. The major mechanisms provided by milk and colostral Igs are (1) preventing microbes from attaching to epithelia, (2) neutralization of viruses and toxins, and (3) augmenting phagocytosis by leukocytes in milk. The major Ig classes in bovine and human milk are IgA, IgG, and IgM. The concentration of different Ig classes in milk and colostrum varies considerably according to species, breed, age, stage of lactation, and health status. In many species, the absorption of Igs from intestine is selective and receptor mediated. However, in ruminants, for example, in the cow, the absorption is non-selective during the first 12–36 h after the parturition. Ruminant neonates are born virtually without Igs; therefore, the colostral Igs are essential for survival. The Ig fraction of milk is utilized commercially as feed supplements and replacers of colostrums, mainly for neonatal calves and pigs in order to prevent gastrointestinal infections. Increasing interest has recently been focused on the development of colostrum-based Ig products which contain specific antibodies for the prevention or treatment of infections in humans. |
