Using a Brix Refractometer to Measure
Passive Transfer of Immunity
"Estimate of serum immunoglobulin G concentration using refractometry with or without caprylic acid fractionation" Morrill, K.M. et al. Journal of Dairy Science July 2013: 4535-4541.
Now that we have the data published in the Journal of Dairy Science I guess we can officially measure passive transfer in calves using blood serum and a Brix refractometer.
The official word is that the most accurate estimate on the Brix is 7.8 that is roughly equal to 12 mg/ml of IgG or you may be more familiar with seeing this value as 1200mg/dL (my estimate on a clinical refractometer for this value is 5.4).
Roughly estimated from the data in the journal article I came up with these values:
Type of Refractometer