Colostrum quality and composition

Colostrum, the first milk produced by the cow before calving, is functionally and compositionally distinct from whole milk. Differences in fat, carbohydrate, protein, vitamin and mineral concentrations provide nutrition for the neonate. A high lipid content is an indispensable source of energy, while protein aids development and vitamins and minerals that are poorly transferred across the placenta can be provided orally. Immunoglobulins within colostrum are essential for the transfer of passive immunity, since the calf is born agammaglobulinaemic. Biologically active factors, including antimicrobial compounds, hormones, growth factors and immune-enhancing compounds, may contribute to immune development, intestinal growth and energy metabolism after birth. Bioactive substances may also direct the maturation of specific tissues via epigenetic effects that occur after parturition has occurred. An appreciation of the differences between colostrum and milk composition may be useful for all stakeholders interested in optimising early life feeding regimens for neonatal calves.