A test based on the concept that the nutritional status of an animal can be estimated by the chemical measurement of some of the components of the blood. It is used to determine the need for variation in the diet of the animal or herd and is thought to be more accurate and to be effective much earlier than the clinical assessments that are more customary as preventive measures. The testing procedure includes the collection of blood samples on a number of occasions during the year and from cows in various stages of nutritional and lactational stress. Only a small group of cows is examined and proper statistical precautions are taken to ensure that conclusions drawn will be valid. A large number of biochemical estimations are carried out on the blood samples, and in some instances on urine samples, so that the animals’ nutritional and metabolic status with respect to most of the significant metabolites can be assessed.
