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

Abstract

BackgroundHeat‐treatment of colostrum is a method developed to reduce calf exposure to pathogens. Infrared (IR) spectroscopy and Brix refractometers can be used for measuring colostral IgG concentration and assessing colostrum quality.ObjectivesTo determine the impact of heat‐treatment on accuracy of IR spectroscopy and Brix refractometers for measuring colostral IgG concentration and assessing colostrum quality before and after heat‐treatment.AnimalsA total of 60 Holstein dairy cows on 8 commercial dairy farms.MethodsA cross‐sectional study was designed to determine the effect of heat‐treatment at 60°C and 63°C each for 30 and 60 minutes duration on colostral IgG concentration measured by the reference radial immunodiffusion (RID) assay, IR spectroscopy, and digital and optical refractometers.ResultsColostrum IgG concentration significantly decreased after heat‐treatment at 63°C for 30 or 60 minutes as measured by RID, but the IgG values remained unchanged when measured by IR spectroscopy and refractometers. The lowest correlation coefficient found between IR spectroscopy (r = 0.70) and RID results was in colostrum heat‐treated at 63°C for 60 minutes. For digital (r = 0.48) and optical (r = 0.50) refractometers, the lowest correlation coefficient was at 63°C for 30 minutes when compared to RID. The accuracy of the IR spectroscopy, digital and optical Brix refractometers was decreased from 91.7 to 80%, 81.7 to 45%, and 80 to 45%, respectively, when colostrum heat‐treated at 63°C for 60 minutes.Conclusions and Clinical ImportanceRadial immunodiffusion, IR spectroscopy, and Brix refractometers exhibit utility for measuring IgG concentration when colostrum heat‐treated at 60°C but does not detect decrease IgG concentrations when heat‐treated at 63°C.

Quantitative assessment and impact of thermal treatment on quality of Holstein dairy cattle colostrum immunoglobulin and viscosity

“…Contrary to our study results, Morrill et al (33) reported a higher concentration of IgG in colostrum ranging from <1 to 200 mg mL -1 with a mean of 68.8 mg mL -1 and 30% of colostrum containing <50 mg mL -1 of IgG. On the other hand, a 72.91 mg mL - Determining the cut-point level for good quality colostrum by means of the Brix refractometer was previously studied (15,35,36,34,38). Our cut-point level of good quality colostrum was determined at ≥20% Brix corresponding to IgG concentration ≥50 mg mL -1 of colostrometer results.…”

“…Similarly, no change in IgG concentration was observed when colostrum was treated at 60°C for 60 min using a commercial on-farm batch pasteurizer (43). Interestingly, similar to our findings, colostrum containing > 50 mg mL -1 and cows was carried out at 63°C for 30 min, 60°C for 60 min and 72°C for 15 s where no effect on the IgG concentration and viscosity of colostrum was observed at 60°C for 60 min compared to a study where no impact on IgG concentration and quality of colostrum treated at 60°C and 63°C for 30 and 60 min was observed (38,45).…”

“…Thermal treatment was performed in a water bath where colostrum was treated at different temperatures and times including 60°C for 60 min, 63.5°C for 30 min and 72.0°C for 15 s (25,38).…”

Quantitative assessment of German Holstein dairy cattle colostrum and impact of thermal treatment on quality of colostrum viscosity and immunoglobulins

“…Our cut-point level of good quality colostrum was determined at ≥ 20%Brix corresponded to ≥ 50 mg mL -1 IgG concentration using colostrometer. Chigerwe et al (11) and Bielmann et al (25) suggested 22%Brix as an optimal cut-point level as compared to the recommended levels (18%, 21% and 23%) for Jersey dairy cattle colostrum (6,13,(23)(24)(25)(26)(27).…”

“…Three thermal treatments (60 °C/60 min, 63.5 °C/30 min and 72.0 °C/15 sec) were performed in a water bath to determine the cut-point temperature that may impact on the viscosity in relation to the IgG concentration (12,13). The water bath was calibrated and adjusted to ± 0.5 °C with an additional digital thermometer (Testo 112 Type NTC, Germany) and thermometer type UT330A (Reichelt Elektronik, Germany).…”