Assessment of Brix refractometry to estimate immunoglobulin G concentration in beef cow colostrum

Abstract

Background Brix refractometry can be used to assess colostral immunoglobulin G (IgG) concentration, but studies identifying Brix percentages to detect high‐ and low‐IgG colostrum are lacking for beef cows and interlaboratory agreement is unknown. Objectives Evaluate Brix refractometer performance and interlaboratory agreement for assessing beef cow colostrum IgG concentration, including determination of thresholds to identify colostrum containing IgG concentrations <100 g/L and ≥150 g/L. Animals Beef cows (n = 416) from 11 cow‐calf operations in Alberta, Canada. Methods Colostral IgG concentrations were measured using radial immunodiffusion (RID) and estimated by Brix refractometry for this retrospective study. Spearman correlation coefficients were assessed between RID and Brix refractometry. Likelihood ratios and misclassification cost‐term analysis were used to determine optimal Brix percentages for detecting colostrum containing IgG concentrations <100 g/L and ≥150 g/L. Concordance correlation coefficient (CCC) and Bland‐Altman analyses were performed for Brix percentages obtained at 3 different laboratories. Results Brix percentages obtained at 3 laboratories were positively correlated with IgG results ( r = 0.72, 0.68, and 0.76, respectively). Colostrum Brix percentages of <24% and ≥30% were optimal for indicating IgG concentrations of <100 g/L and ≥150 g/L, respectively. Interlaboratory agreement was substantial, with CCC ranging from 0.89 to 0.96 and Bland‐Altman analysis showing small mean differences (−1.2% to 0.09% Brix) and narrow limits of agreements (−4.8% to 2.4% Brix) among laboratories. Conclusions and Clinical Importance Brix refractometry shows good potential for reliably estimating IgG concentrations in beef cow colostrum across multiple laboratories and can be recommended to aid colostrum management decisions on farms.

Determining Immunoglobulin Content of Bovine Colostrum and Factors Affecting the Outcome: A Review

“…In general, beef cows should have a higher Ig concentration in the colostrum than dairy cows. This opinion is concordant with the studies of Gamsjäger et al (2020) [ 54 ], in which the cut-off points for low-IgG colostrum and high IgG colostrum for 416 colostrum samples from one beef breed deviate strongly from the normally used cut-off point of 50 mg IgG mL −1 . The cut-off point for low-IgG colostrum was at <100 mg mL −1, and the cut-off point for high-IgG colostrum was at ≥150 mg mL −1 .…”

“…However, even in this study, the IgG concentration in the colostrum varied greatly (19.2–264.7 mg mL −1 ). These variations are also found in studies with dairy breeds [ 54 ]. The average IgG concentration measured using RID in a study by Elsohaby et al (2018) [ 43 ], including beef cows, was 143.2 mg mL −1 , just below the previously indicated cut-off point of 150 mg mL −1 .…”

“…¹ Holstein-Friesian; ² New Zealand Holstein-Friesian; ³ Brown Swiss; ⁴ Jersey; ⁵ Norwegian Red; ⁶ mixed beef breeds; ⁷ Charolais; ⁸ Holstein-Friesian × Charolais; ⁹ Montbéliarde; ¹⁰ Holstein-Friesian × Montbéliarde; ¹¹ Pinzgauer; ¹² Simmental; ¹³ Rhetic Gray; ¹⁴ Murnau-Werdenfelds; ¹⁵ Original Braunvieh. [ 5 , 6 , 8 , 11 , 13 , 20 , 31 , 44 , 45 , 46 , 53 , 54 , 60 , 68 , 69 , 86 , 87 , 88 , 89 ].…”

Evaluation of 3 refractometers to determine transfer of passive immunity in neonatal beef calves

“…36,37 may elect to use the Brix refractometer for serum IgG evaluation as well. On the other hand, many veterinarians have DSTP and OSTP available in their veterinary practice because of their multipurpose utility (eg, urine specific gravity, STP in adults and neonates), and their use should be encouraged for assessment of TPI in beef calves.In conclusion, DSTP, OSTP, and DBRIX all showed good utility for assessment of TPI status in neonatal beef calves, particularly for identification of calves with IgG concentrations below the target concentrations recommended recently for beef calves (IgG <16 or < 24 g/L).…”

Assessment of microRNA profiles in small extracellular vesicles isolated from bovine colostrum with different immunoglobulin G concentrations

“…Colostrum samples were collected from 6 beef heifers (first parity) and 2 beef cows (third or higher parity) from 4 different privately owned cow-calf operations with either purebred Angus, Hereford, or Angus × Hereford crossbreds in southern Alberta, Canada. These samples were from 416 colostrum samples with extremely different IgG concentrations (Gamsjäger et al, 2020). Twenty milliliters of colostrum was collected manually, pooled from all teats into a clean plastic sampling cup, and stored at −80°C (Pearson et al, 2019a,b;Gamsjäger et al, 2020).…”