“Only by measuring the proportion of immunoglobulins in the colostrum can you know the quality of your colostrum,” says Nicolien Spinhoven. Good colostrum contains antibodies, immunoglobulins (IgG). But it is not just antibodies that make colostrum a unique product. There are more ‘life substances’ in the colostrum: white blood cells, growth hormones, vitamins, minerals, protein, and energy and substances that have a positive effect on the development of the small intestine. Thanks to their ‘life experience’, older cows have better quality colostrum. “Although in practice you see that heifers can achieve at least as good a Brix value in colostrum as older cows,” says Nicolien.
At least 65 grams of IgG per liter
Good colostrum contains at least 65 grams of IgG per liter. The first colostrum contains the highest IgG concentration, in the second colostrum this concentration is already halved. With a brix meter you can read the quality of the colostrum. You place a drop of colostrum on the glass. Then you look through the lens to read the brix value. Good colostrum has a brix value of at least 23%, which stands for 68 grams of igG per liter. View the complete schedule of brix and IgG values here. The refractometer measures the density of colostrum (total dry matter content of fat, protein and lactose). Colostrum with a high density is also rich in antibodies.
Remember to calibrate
Don’t forget to calibrate your refractometer before you start. In this video Johan explains how to do that. With a practical tip to reset your refractometer to 0:
Viewing tip
In this Dutch vlog, dairy farmer Rachelle explains how she uses the refractometer.