Validation Repeatability of Measurement of Antibody Response to Ovalbumin in Beef Cattle

The objectives of this experiment were to evaluate the pattern of antibody response to ovalbumin as a test antigen in beef cattle, and to estimate the repeatability of the measurement of that response. Purebred Angus cows and calves were immunized with ovalbumin and later tested for antibody response. Six animals were sampled 7 d post-initial immunization to characterize primary antibody response and at 3, 5, and 7 d post-secondary immunization to characterize secondary antibody response. Increases in level of IgG specific for ovalbumin were more rapid in calves than in cows but gradually, measured levels became similar. Secondary responses were measurable on all specified dates, but primary response was not evident at d 7. Correlations between successive samples on animals indicated that the measurements were repeatable (R = .73) for secondary response. These data indicate that ovalbumin is an acceptable test antigen for eliciting a humoral immune response in beef cattle and that measurement of secondary response to ovalbumin can be evaluated in beef cattle at 5 or 7 d post-secondary immunization.