Comparison of the levels of selected specific antibodies in the immunoglobulin G of colostrum versus milk and serum in dairy cows (Bos taurus).

Commercial products containing immunoglobulin G (IgG) sourced from colostrum, milk, and/or serum may be used to supplement or replace maternal colostrum in newborn dairy calves. To determine if antibody specificities in bovine milk and serum IgG differ from colostrum IgG, we sampled serum, colostrum (1 to 2 hours post-partum), and milk (day 5 post-partum) from 24 dairy heifers or cows. Specific antibodies [IgG class (H&L)] to 8 common pathogens were measured using enzyme-linked immunosorbent assays (ELISAs). Immunoglobin G1 and IgG2 subclass-specific ELISAs were performed for 3 of these pathogens. Colostrum-derived IgG contained more specific antibodies to rotavirus [IgG (H&L) and IgG1] and to IgG (H&L) of bovine respiratory syncytial virus (BRSV), bovine parainfluenza-3 virus (BPI₃V), Staphylococcus aureus, Escherichia coli F5 (K99), and bovine coronavirus than milk IgG. Colostral IgG contained more antibodies to BRSV (IgG1), rotavirus (IgG1), and IgG (H&L) specific for BRSV, bovine herpesvirus-1 (BHV-1), BPI₃V, E. coli F5 (K99), and Streptococcus uberis than serum IgG. Compared to serum, milk contained more IgG (H&L) antibody to BRSV, BHV-1, and BPI₃V, IgG1-specific BRSV, and rotavirus. These data indicate that IgG derived from colostrum delivers more specific antibodies to these endemic pathogens of calves compared to IgG sourced from milk or serum. In addition, the IgG1 subclass predominates in milk and colostrum, and both deliver a similar spectrum of antibodies.