Total protein assessment in blood serum of calves and its evaluation using the optical or digital refractometer is the easiest method to identify problems in the calf management. The blood samples are collected from second to seventh day of calf age and are kept in the test tubes for cattle containing separation granules. Also portable centrifugal machine for serum separation can be used. Optical or digital refractometers can provide a tentative assessment of the total protein level. The calf is well-fed, when the resulting level of total protein is ≥ 5.5 g/dl, or 55 g/l of its blood serum. The considerable number of refractometers has the scale in g/dl of blood serum (1 g/dl = 10 g/l). The reference value in the case of the universal refractometers is above 8,4 % Brix.