Antibody response in lacteal secretions of cows after immunization with various concentrations of staphylococcal and streptococcal antigens.

A total of 55 lactating Holstein cows were randomly allocated to 6 groups. Five of these groups (No. 2 through 6) were inoculated on 2 occasions in the region of the external inguinal lymph node with various concentrations of 3 bacterial antigens. Saline solution was administered to group 6 as a control. The antigen preparations consisted of a Staphylococcus aureus bacterin, a Streptococcus agalactiae bacterin, and staphylococcal alpha-toxoid. These antigens were administered as a composite preparation suspended in saline solution. The concentration of antibody in the lacteal secretions, represented by immunoglobulin G specific for each of the 3 vaccine antigens, was monitored during the 18-week experimental period by enzyme-linked immunosorbent assay. The concentration of each of the 3 vaccine components which was required to stimulate a maximal immune response in the lactating gland appears to have been established.