Dunn, AmandaDuffy, CatherineGordon, AlanMorrison, StevenArgűello, AnastasioWelsh, MichaelEarley, Bernadette2021-06-142021-06-142017-11-02Dunn, A., Duffy, C., Gordon, A., Morrison, S., Argűello, A., Welsh, M. and Earley, B. (2017) ‘Comparison of single radial immunodiffusion and ELISA for the quantification of immunoglobulin G in bovine colostrum, milk and calf sera’, Journal of Applied Animal Research, 46(1), pp. 758–765. doi: 10.1080/09712119.2017.1394860.0971-2119https://doi.org/10.1080/09712119.2017.1394860Publication history: Accepted - 12 October 2017; Published online - 02 November 2017.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.en© 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.ELISAsingle radial immunodiffusionzinc sulphate turbidity testBrix refractometerIgGcalfcolostrumArticle