Rapid assessment of bovine colostrum quality: How reliable are transmission infrared spectroscopy and digital and optical refractometers?

Abstract

The objectives of this study were to evaluate the performance of the transmission infrared (IR) spectroscopic method and digital and optical Brix refractometers for measurement of colostral IgG concentration and assessment of colostrum quality of dairy cows. Colostrum samples (n = 258) were collected from Holstein cows on 30 commercial dairy farms in Nova Scotia and Newfoundland, Canada. Colostral IgG concentrations of 255 samples were measured by the reference radial immunodiffusion (RID) assay and IR spectroscopy. The Brix scores were determined on 240 of these samples using both the digital and optical Brix refractometers. Approximately half (48%) of the colostrum samples had RID IgG concentrations <50 g/L, which was the cut-point for poor quality. The correlation between RID and IR IgG concentrations was 0.88. The correlations between RID IgG concentration and Brix scores, as determined by the digital and optical refractometers, were 0.72 and 0.71, respectively. The optimal cutoff levels for distinguishing good- and poor-quality colostrum using IR spectroscopy, and digital and optical Brix refractometers were at 35 g/L and 23% Brix, respectively. The IR spectroscopy showed higher sensitivity (90%) and specificity (86%) than the digital (74 and 80%, respectively) and optical (73 and 80%, respectively) Brix refractometers for assessment of colostrum quality, as compared with RID. In conclusion, the transmission-IR spectroscopy is a rapid and accurate method for assessing colostrum quality, but is a laboratory-based method, whereas Brix refractometers were less accurate but could be used on-farm.

Brix Refractometry of Colostrum from Primiparous Dairy Cows and New-Born Calf Blood Serum in the Evaluation of Failure of Passive Transfer

“…In our study we showed that Brix values were highly correlated with colostral IgG analyzed by RID. This fi nding is similar to the results of other research groups [1,15,34,35], who also found a moderate to high correlation between % Brix and IgG measured by RID. Besides we found that there was a signifi cant, but somewhat lower, correlation between the results obtained with the Brix refractometer and the concentration of colostral whey IgG measured with APE.…”

Effect of Heat‐treatment on Accuracy of Infrared Spectroscopy and Digital and Optical Brix Refractometers for Measuring Immunoglobulin G Concentration in Bovine Colostrum

“…For the IR spectroscopy, the cut‐point of 50 g/L provided strong specificity and moderate sensitivity values across the unheated and heat‐treated colostrum (Table ). The accuracy of the IR spectroscopy (91.7%) to differentiate between unheated poor and good quality colostrum was higher than that reported in previous studies . However, the accuracy of the IR instrument to correctly determine quality of heat‐treated colostrum was lower with more samples with poor IgG levels categorized as adequate.…”

“…The IR spectroscopy and digital and optical Brix refractometers had a high-to-moderate agreement with the reference RID assay for assessing the quality of unheated colostrum and colostrum heat-treated at 60°C, which is similar to a previously report by the authors for unheated colostrum. 37 However, when colostrum heat-treated at 63°C, there was a poor agreement between the 3 methods and RID assay ( Table 1).…”

“…The accuracy of the IR spectroscopy (91.7%) to differentiate between unheated poor and good quality colostrum was higher than that reported in previous studies. 11,12,37 However, the accuracy of the IR instrument to correctly determine quality of heat-treated colostrum was lower with more samples with poor IgG levels categorized as adequate. For Brix refractometers, the cut-point 22% Brix showed strong sensitivity and moderate specificity values across the unheated and heat-treated colostrum.…”

Evaluation of 2 different treatment procedures after calving to improve harvesting of high-quantity and high-quality colostrum

“…It remains speculative why there was only poor agreement between the 2 methods. According to Elsohaby et al (2017), variations in the correlation coefficients could be related to the different non-IgG components in colostrum. The measurement via Brix refractometry assesses IgG concentrations indirectly, through assessing total dissolved solids that affect the sucrose concentration.…”