Invited review: The importance of colostrum in the newborn dairy calf

It is critical that bovine maternal colostrum is fed to newborn calves during their first hours of life. Colostrum is the secretion a cow produces after mammary involution that is rich in various nutrients. In addition to the nutritive value for newborn calves, immunoglobulins are of interest due to their role in developing the naive immune system of calves at birth. The process by which a calf acquires immunity via absorption of immunoglobulins is defined as passive immunity. When calves consume an adequate amount of immunoglobulins, they are classified as having successful passive immunity (SPI). In contrast, if they are deprived of adequate colostrum, they are considered to have had a failure of transfer of passive immunity (FPI). Transfer of passive immunity is assessed by measuring serum IgG concentrations at 24 to 48 h of age. The major factors that influence whether a calf has SPI or FPI are colostrum IgG concentration, quantity fed, and age of calf at colostrum feeding. Monitoring apparent efficiency of immunoglobulin absorption in calves is often recommended to evaluate overall colostrum management practices. Serum IgG analyses can be determined with direct (radial immunodiffusion) or indirect (refractometry) methods and used to assess SPI or FPI prevalence.

Automated summary

Feeding maternal colostrum to newborn calves in their first hours of life is crucial for their development. Colostrum contains various nutrients and immunoglobulins, which play a significant role in building the calves' immune system. The successful transfer of passive immunity is determined by the calf's consumption of an adequate amount of immunoglobulins. Factors such as colostrum IgG concentration, quantity fed, and age of the calf at colostrum feeding influence the outcome of passive immunity. Monitoring serum IgG concentrations is recommended to assess the overall management of colostrum. Apparent efficiency of immunoglobulin absorption can be determined through direct or indirect methods and used to evaluate the prevalence of successful or failed passive immunity transfer.