The diagnostic accuracy of the Brix refractometer in determining mare colostrum with high and low immunoglobulin G concentrations.

This research aimed to evaluate the effectiveness of the Brix refractometer in measuring immunoglobulin G (IgG) levels in mare colostrum. Findings suggest that the device can accurately determine colostra with both low and high IgG concentrations.

Research Objective

The purpose of this study was to assess the diagnostic accuracy of the Brix refractometer, a digital device used for estimating Immunoglobulin (IgG) concentration in mare colostrum. This is due to the limited study on the appropriate thresholds for using the device to detect either high or low IgG concentrations in mare colostrum.

Methods

• Participants of the study were 217 Arabian mares. Their colostral IgG concentrations were both measured with the radial immunodiffusion assay as well as estimated with the Brix refractometer.
• The thresholds for the Brix refractometer were then determined through a receiver operating characteristics analysis; this analysis looks at the true positive rate (sensitivity) against the false positive rate (1-specificity) allowing them to determine the best Brix threshold.

Results

• The average IgG concentration in the colostrum was 83.73±2.46 g/L. Upon calculating the correlation between the IgG concentrations and the Brix percentages, they got a high Pearson’s correlation coefficient of 0.78.
• The optimal refractometer thresholds for the determination of colostral IgG concentrations of <50, <60, >80, >100 and >125 g/L were ascertained to be <19.6%, <20.1%, >21.6%, >23.6%, and >27.3%, respectively.
• The sensitivity and specificity of the refractometer were also calculated for the different IgG concentrations, with values ranging from 75.0% to 89.3% for sensitivity, and 73.7% to 90.4% for specificity.

Conclusions

In conclusion,the Brix refractometer demonstrated a solid performance in identifying low and high IgG concentrations in mare colostrum. Its use can therefore help quickly identify foals at risk of failure in transfer of passive immunity, which occurs when they receive poor-quality colostrum. This allows for early interventions and better survival rates among newborn horses.