Contradictions on colostrum IgG levels and Brix values are real and can be explained. Response to letter by Lombard<i>et al</i>. (2022)

Schalich, Kasey M; Selvaraj, Vimal

doi:10.1093/jas/skac120

Cited by 3 publications

(1 citation statement)

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“…An examination of Figures 1A , B shows that as %Brix scores increase, the digital refractometer does not measure as well, particularly when the Brix scores are 30% or higher. This observation is likely caused by increasing concentrations of fat, casein, and other macromolecules that are insoluble in water, thus impacting the Brix refractometer reading ( 13 ).…”

Section: Discussionmentioning

confidence: 99%

Investigation of brix refractometry for estimating bovine colostrum immunoglobulin G concentration

Sockett,

Breuer,

Smith

et al. 2023

Front. Vet. Sci.

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Many dairy operations uses a Brix refractometer to assess the quality of first-milking colostrum. This study investigated whether a digital Brix refractometer could be used in a model to predict colostrum IgG concentration and whether more than one %Brix threshold could be used for different colostrum IgG concentrations. Colostrum from 182 animals was tested using a digital Brix refractometer and by single radial immunodiffusion. Statistical analysis, using simple linear regression to relate %Brix results with corresponding colostral IgG concentration, and receiver operating characteristic (ROC) analysis were used to identify %Brix cutoffs that had no false positive results. Colostral IgG concentrations from digital Brix refractometry had a R2 value of 0.818 and a S-value of 21.7 g/L. The large S-value shows that a digital Brix refractometer should not be used in a model to predict colostrum IgG concentration. However, %Brix scores of 19.0, 22.0, 25.0 and 30.0 percent can be used to estimate minimum colostral IgG concentrations of 25, 50, 75 and 100 g/L. These four cutoffs can be used to strategically feed smaller volumes of colostrum to newborn calves. Smaller volumes may reduce unwanted side effects and shorten the time interval in which calves refuse to nurse, while still delivering an adequate mass of IgG to have successful transfer of passive immunity.

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Section: Discussionmentioning

confidence: 99%