Validation of The Digital Brix Refractometer to Evaluate Immunoglobulin G Concentration (IgG) in Bovine Colostrum

In recent years, there has been an increasing interest in usage of portable lightweight and accurate instrument such as refractometer in dairy industry. This paper attempts to show that each one of mentioned instruments in various cut-points what will be their performance. Randomly, 80 cattle (primiparous and multiparous) selected and lactation number, calving ease score, volume of colostrum at first-milking were recorded and somatic cell count (SCC), total solid (TS), specific gravity, Brix% reading and immunologlobolin G concentration of colostrum sample measured. Thirtytwo percent of colostrum samples in the current study had IgG concentration of lower than 50 g/L. The results showed an acceptable correlation (R2=0.679) between Brix% reading and IgG concentration measured by enzyme linked immunoabsorbant assay (ELISA), also interaction of hydrometer method and digital Brix refractometer (%) had a strong and positive (R2=0.711) correlation. Performance of digital Brix refractometer for identifying low quality colostrum elevated at cut-point 24%, so that the sensivity and specificity of instrument in mentioned cut-point were 85.5% and 96%, respectively. The current results confirmed digital Brix refractometer is accurate and have a good correlation with IgG concentration of colostrum, and diagnostic characteristics test of device could be better if used of fixed colostrum volume for measurement, but in the colostrum samples with high SCC adequacy of this portable on-farm device falls down.