Using a Brix Refractometer to Evaluate Colostrum Quality
On May 8, 2016 Dr. Jim Quigley published Calf Note #187 on this topic. To go to that note click HERE.
Jim summarizes the finding of three studies done in 2013, 14 and 15 in one very handy table (Table 1.)
Using these data he worked out another table showing the estimated connection between BRIX readings and serum IgG values (g/L). Table 2 shows that a BRIX reading of 8.0% is about equal to the standard we have been using for minimum passive transfer of 10g/L IgG.
Using total serum protein values (from a clinical refractometer) I have been recommending these performance standards:
1. 90% calves testing at 5.0g/dl or greater
2. 75% calves testing at 5.5g/dl or greater
If we make the conversion from these values to those from a BRIX refractometer then my recommended performance standards are:
1. 90% calves testing at 8.0% or greater
2. 75% calves testing at 8.5% or greater
It should be uncommon to get readings as high as 9.5-10.0. While high readings may indicate superior passive transfer more often these very high readings suggest significant dehydration in the calf.