The object of this paper is to discuss the practical application of blood profiles and the value of blood profiles as an advisory aid in the field. For this purpose, an attempt has been made to quantify the ‘success rate’ of blood profiles on a case study basis. It is hoped that the paper will serve to stimulate discussion by being as objective as possible. It is not presented as an original scientific paper and should not be interpreted as such.

The productivity of the dairy herd is primarily dependent on the metabolic and nutritional status of each dairy cow. All too frequently, there is a tendency for high output demands - milk and calves - to be associated with inadequate feed inputs, resulting in imbalances of body metabolites, which, if sustained, eventually become clinically apparent as ‘production diseases’ such as hypocalcaemia and hypomagnesaemia.