On-Farm Testing of Colostrum Quality
In a recent report of on-farm testing of colostrum quality both a Colostrometer and Brix refractometer were used. For comparison the research team used an in-laboratory test as well.
The research team reported, "If a sample tests lower than 80g/l (grams per liter) on the Colostrometer, there is a 60.6% chance that is truly poor quality [less than 50g/l] and if it tests higher than 80g/l, a 92% chance that it is of adequate quality."
"A sample testing lower than 23% Brix has a 61% chance of being truly inadequate, whereas a sample testing higher than 23% Brix has an 85.5% chance of being adequate." (p1880)
So, why are we testing? We especially want to avoid feeding inadequate quality colostrum - less than 50g/l value. Remember we are trying to feed at least 200 grams of antibodies in the first four hours - that is our minimum threshold
Rereading the text above we find that both the Colostrometer (80g/l) and Brix refractometer (23%) will identify about 60 percent of the samples that are truly poor quality [50g/l] if we use these values as lower quality thresholds. The new information in this research for me was the need for using a higher threshold when using the Colostrometer if I want to be confident that the colostrum is not of poor quality - I have been using 50g/l (the dividing line between the green and yellow zone on the Colostrometer) and I need to think about using a higher value.
Among these 13 herds in Alberta, Canada, province the antibody levels among cows varied widely from a minimum of 8g/l to a maximum of 129g/l. More of the low antibody samples came from first and second lactation cows compared to those third lactation and greater.
Reference: Bartier, A. L. and Others, "Evaluation of on-farm tools for colostrum quality measurement." Journal of Dairy Science 98:1878-1884 March 2015