Comparison of radial immunodiffusion, turbidimetric immunoassay, and Brix refractometry for determining bovine colostrum quality

Abstract

Graphical Abstract Summary: This study evaluated the agreement of turbidimetric immunoassay (TIA) and Brix % with the reference method, radial immunodiffusion (RID), for evaluation of colostrum quality. The results show a strong correlation between RID and TIA as well as Brix %. However, a systematic and proportional bias was observed for TIA, which indicates caution should be used for the direct comparison of immunoglobulin G (IgG) results determined via RID.