Colostrum is the first mammary glands secretion at parturition. In ruminants, the neonates are born agammaglobulinemic because there is no Ig transfer through the placenta. Thus, passive immunization through the colostrum helps the newborn to contend pathogens and survive the first weeks of life. The gold standard of Ig and/or Ig isotypes: IgG1 & IgG2, IgM and IgA is their determination by an immunoassay such as ELISA. However, these assays require laboratory equipment, are time consuming and therefore not applicable under farm conditions. On site, rapid assays such as Colostrometer or Brix refractometer are used. To date, many dairy farms are equipped with on-line computerized data acquisition systems. The aim of the study was to calibrate data collected on-line for evaluating the level of immunoglobulins in the colostrum. The study included 4 dairy farms with parlors equipped with an on-line computerized Afimilk Herd Management system including AfiLab milk spectrometer (Afimilk, Israel). Samples were tested by Colostrometer and by Brix calibrated for Ig. Total IgG was determined by ELISA BIO k 165/2 kit (Bio-X Diagnostics S.A., 5580 Rochefort, Belgium). In total, 205 samples were collected from 127 cows representing first, second and third milking postpartum. Correlations were calculated for 2 scenarios. (A) with first, second and third milking colostrum, and (B), only with first milking. The correlation of IgG level to Colostrometer (R²) measurement was 0.79 for A and 0.58 for B, for IgG level to Brix it was 0.76 and 0.43 respectively. The automated in parlor real time analysis of Ig levels with the AfiLab spectrometer correlations were 0.7 for A and 0.53 for B. Assuming practice of dichotomic IgG cutoff at 50 mg/mL, the sensitivity was 88.2 and specificity 87.9%. In conclusion, it was shown that AfiLab milk spectrometer provided information on the quality of colostrum immunoglobulins in real time milking, more sensitive than Colostrometer and Brix determinations. Thus, it is possible to create a “bank” of 'good' colostrum by compiling the data obtained by the Afilab analyzers, which is now implemented into the Afimilk system.