Determine your herd’s individual cut-off limit
The threshold of Brix 22 (corresponding to an antibody content of over 50 g/L) in the colostrum is often cited but should be ignored. Instead, the aim should be to implement a colostrum strategy that uses the best possible colostrum available in the individual herd.
To do this, an individual cut off limit (Brix value) should be established for the herd, based on the average and variation in the antibody content in colostrum among the herd's own cows. This ensures the best possible start for all the new-born calves in the herd. At the same time, efforts should be made to raise the level of the herd's colostrum quality, so the cut-off threshold can be raised as much as possible – for example through focus on the feed and management of dry cows, and milking the cow as soon as possible after calving.
It is not possible to predict antibodies in colostrum
The antibody content of colostrum cannot be predicted — even based on the cow’s lactation number. Statistically, there is a greater chance that older cows produce milk with a high content of antibodies. However, in practice some heifers produce high-quality colostrum and some older cows can produce low-quality colostrum.
Similarly, the consistency or colour of the colostrum is not an accurate guide to colostrum quality.
This means that if the colostrum is given directly from the cow to the calf without testing, the level of antibodies received will be random and determined by chance.