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Comparison of single radial immunodiffusion and ELISA for the quantification of immunoglobulin G in bovine colostrum, milk and calf sera

Dunn, Amanda, Duffy, Catherine, Gordon, Alan, Morrison, Steven, Argűello, Anastasio, Welsh, Michael, Earley, Bernadette
Journal of applied animal research 2018 v.46 no.1 pp. 758-765
Holstein, blood sampling, blood serum, cow colostrum, dairy calves, enzyme-linked immunosorbent assay, immunoglobulin G, milk, turbidity, zinc sulfate
The overall objective was to compare immunoglobulin G (IgG) concentrations measured by single radial immunodiffusion (sRID) and ELISA-based methods in samples of bovine colostrum and transition milk from contrasting breed types (Limousin × Friesian (n = 10) and Holstein (n = 10)). Jugular blood samples were collected at 48 h post-birth from beef (n = 10) and dairy (n = 10) calves and sera harvested subsequent to colostrum consumption. Absolute colostrum IgG values determined by ELISA showed poor agreement with mean (SD) IgG values measured using sRID, fixed bias (sRID – ELISA) was 31.89 (±9.84) mg/mL; having wide limits of agreement (12.61–51.17) and a low concordance coefficient (0.26). The agreement between ELISA and sRID when measuring serum IgG was greater than that of colostrum, fixed bias (sRID – ELISA) was 12.36 (±6.60) mg/mL; having narrower limits of agreement (−0.58 to 25.30) and serum IgG concentrations had a greater concordance coefficient (0.44) between samples. Calf sera IgG measured using the indirect zinc sulphate turbidity test showed a strong correlation with the sRID and ELISA methods (P < .001), R² = 0.78 and R² = 0.77 respectively. Overall, the ELISA and sRID methodologies had a strong positive association with almost a twofold (1.8) difference between values; therefore, they provide diverse absolute values of IgG concentration.