The aim of this study was to evaluate the usefulness of Digital Brix refractometer as one of the methods for measuring the concentration of immunoglobulin G (IgG) in sows colostrum after comparing with the results obtained by laboratory testing of colostrum samples with method of radial immunodiffusion (RID). Next step was to determine the amount of immunoglobulin G (IgG) in sow colostrum 0 hours of the start of farrowing and the impact of the concentration of immunoglobulin G (IgG) on the health status and production performance of piglets to the weaning. The study was conducted on 120 cows and gilts on two commercial reproduction farm in eastern Croatia (Farm 1 and Farm 2) that are in the system of two different hybrid programs (A and B) engaged in the production and breeding of pigs for fattening to the average body weight of 25 kg. From each sow, during the first hour after the farrowing, through three cycles of sampling, from one of the front teats were taken (milked by hand) into a sterile test tube of 10 mL of colostrum for Refractometric analysis. Colostrum was stored immediately after collection at a temperature of -20°C. Besides the above mentioned 640 samples of colostrum for refractometers there was collected a total of 100 samples for radial immunodiffusion (RID), in parallel with the samples for measurement using a digital Brix refractometer. These samples were taken at the same time on the following two farms of the 50 samples, on each farm also in 3 occasions of sows that have different numbers of farrowing. Frozen colostrum samples were used for laboratory tests in which was determined the chemical composition of colostrum and immunoglobulin G (IgG). RID values determined in this study was between 60 and 80 g/L. Compared with the previously published data our values was lower, but they did not have a negative effect on the survival of piglets during the first days of life. Brix values determined in colostrum of sows were between 23.6% and 27.7%. Brix values above 22% indicate a good quality of colostrum and high concentration of immunoglobulin G. Average Brix value determined by analyzing a sample of colostrum for 8 lactation at two different farms indicate that the sows colostrum on the farm A had a slightly higher value compared with the sows colostrum from farm B, but these values were not statistically significant. Notable are slightly lower Brix value in the second and third lactation, followed by a linear increase in value, which is consistent with previous research. Comparison RID and Brix method of determining the content and concentration of immunoglobulin G resulted in a clear linear relationship between the calculated results. On farm A correlation coefficient between Brix and RID was r = 0.81, p <0.001 and on the farm B the correlation coefficient was r = 0.75, p <0.001. Taking into consideration high correlation coefficient, on the basis of a submitted, we can conclude that Brix refractometer provides affordable and reliable estimate of IgG concentration in sow colostrum and as such it can be used in wide practice. The concentrations of IgG in sow colostrum measured by using a digital Brix refractometer does not differ from the concentration determined by conventional methods. There was no difference between concentrations of IgG in the content of colostrum from different animals immediately after farrowing. During the research there was determined the production traits of sows and the piglets during the suckling period and at the same period there was observed and recorded health status of piglets. There were no statistically significant differences between two different sows hybrid on the two farms in terms of all determined reproductive and productive parameters. These results confirm the fact that the highly intensive pig production today uses hybrids that are very similar in terms of its properties. There were no statistically significant differences in the number of piglets, the average body weight of piglets at the weaning, the average litter weight at weaning and average daily gain between pigs at both farms. Between groups of piglets there were no statistically significant differences in rates of illness from pneumonia and diarrhea, and in terms of mortality rates of piglets. The determined values indicate on the high level of biosecurity and hygiene measures implemented on farms involved in the survey, since the rate of disease as well as the mortality rate was very low. The concentration of IgG significantly affects the health status and production performance of piglets to the weaning. The determined value of the content and concentration of IgG in the sows colostrum on both farms and established production traits and health status of piglets, suggest an association between concentration and content of IgG determined by Brix and RID method with production specifications and the health status of piglets during the suckling period. This indicates that the application of Brix refractometry can be substantially for the producers, especially in the most sensitive part of the production, and it is the breeding of the piglets. The method of determined the content of IgG in the sows colostrum has an advantages over the other methods of assessing the level of IgG, since the Brix refractometer is inexpensive, readily available, less reliable and less susceptible to variations in the temperature of colostrum, season and other factors, and requires minimal equipment and training. Evaluation of colostrum can be conducted at sows directly after the farrowing, which can improve the possibility for producers for making the valid and timely decisions based on test results.