Ganz Sebastian, Bülte Michael, Gajewski Zdzislaw, Wehrend Axel
Tierarztl Prax Ausg G Grosstiere Nutztiere. 2018 Jun;46(3):178-189. doi: 10.15653/TPG-180144. Epub 2018 Jun 14.
The best studied substances in bovine colostrum are the immunoglobulins. They are absorbed in the small intestine of the neonate by pinocytosis. The Fc-receptor is not highly involved in this process in calves compared to other species. However, this receptor plays a crucial role in the transport of immunoglobulins from the circulation of the dam to the udder and, therefore, into the colostrum. During colostrogenesis, which starts up to 8 weeks prior to parturition, up to 500 g of immunoglobulins are transferred daily by this process. In addition, other components of the bovine colostrum have biological activity. Colostrum-derived growth factors, including IGF-1, EGF and TGF, influence the differentiation of the epithelial cells of the gastrointestinal tract and, therefore, its development. In the udder of the dam, they are involved in various mechanisms of adaption throughout the lactation period. Colostral leucocytes are also transported from the colostrum into the circulation of the offspring, this by a process termed cellular migration. These cells have a specific immunological memory and support the calf in the development of an immune response against specific pathogens the dam was exposed to earlier. Colostral enzymes can be used as an indirect parameter to control for an adequate colostrum supply of the calf (e.g. γ-glutamyltransferase) or have an unspecific antimicrobial potential capacity (e.g. lactate peroxidase, lactoferrin, lysozymes). Vitamins, fats, proteins and mass and trace elements in the colostrum are essential nutrients for the bovine neonate because of the great change in the requirements for the neonatal organism from preto postnatal life. The impact of hormones and other components of the colostrum is still mostly unclear. The composition of the colostrum in the individual cow is influenced by numerous factors, including the number of calvings, the amount of colostrum formed and breed of the dam.
牛初乳中研究得最为透彻的物质是免疫球蛋白。它们通过胞饮作用在新生动物的小肠中被吸收。与其他物种相比，Fc受体在犊牛的这一过程中参与程度不高。然而，该受体在免疫球蛋白从母体循环转运至乳房并进而进入初乳的过程中起着关键作用。在分娩前长达8周就开始的初乳生成过程中，每天通过这一过程可转运多达500克的免疫球蛋白。此外，牛初乳的其他成分也具有生物活性。初乳衍生的生长因子，包括胰岛素样生长因子-1（IGF-1）、表皮生长因子（EGF）和转化生长因子（TGF），会影响胃肠道上皮细胞的分化，进而影响其发育。在母体的乳房中，它们在整个泌乳期参与各种适应机制。初乳中的白细胞也通过一种称为细胞迁移的过程从初乳转运至后代的循环系统中。这些细胞具有特定的免疫记忆，并在犊牛针对母体先前接触过的特定病原体产生免疫反应的过程中提供支持。初乳中的酶可以用作控制犊牛初乳供应是否充足的间接参数（例如γ-谷氨酰转移酶），或者具有非特异性抗菌潜能（例如乳酸过氧化物酶、乳铁蛋白、溶菌酶）。由于新生牛机体从产前到产后生活的需求发生了巨大变化，初乳中的维生素、脂肪、蛋白质以及大量和微量元素是新生牛至关重要的营养物质。初乳中激素和其他成分的影响大多仍不清楚。个体奶牛初乳的成分受多种因素影响，包括产犊次数、初乳产量以及母体的品种。
