It is important to note that while the Brix refractometer significantly helps us measure colostrum quality, we are still lacking a reliable, easy, cowside test to measure the level of contamination in colostrum. High bacterial counts in colostrum may interfere with passive transfer of immunity, and pose a risk of making the calf sick directly from the colostrum, despite having high levels of IgG.
Colostrum that is clean but does not make the cut on IgG levels can be fed to older calves for the first few days of life, and calves will benefit both from the nutritional content of colostrum and the high IgG levels, which help to protect the gut locally. If not enough high quality colostrum is available for their calves’ needs, or if colostrum contamination is suspected, producers should consider using a colostrum supplement or colostrum replacement product as appropriate to the situation. Colostrum supplements contain less than 100g IgG and are designed for the calf that is getting at least some maternal colostrum already. Colostrum replacers are defined as containing over 100g of IgG and are designed to be used in place of maternal colostrum. They are also a great choice when cleanliness of colostrum is suspect.
An evaluation of Brix refractometry instruments for measurement of colostrum quality in dairy cattle. V. Bielmann ,*1 J. Gillan ,* N. R. Perkins ,* A. L. Skidmore ,† S. Godden ,‡ and K. E. Leslie * J. Dairy Sci. 93:3713–3721