One of the stages of the dairy farming technological process is the biochemical study of the animal blood. At the same time, great importance is given to the preanalytical stage, since non-compliance with the rules for the selection, transportation and storage of blood samples in laboratory analysis can lead to 50-70% errors. The creation and regular implementation of a system of measures for identifying and preventing unacceptable errors is an integral part of the process of performing reliable laboratory research. However, the concept of reliable laboratory results quality assurance as a consistent and correct implementation of the analytical stage only is very narrow and cannot be considered a full and sufficient basis for ensuring the guaranteed quality of the work of clinical laboratory diagnostics specialists. The paper studies the influence of factors on the preanalytical stage (methods and terms of blood samples storage), which may have an interfering effect on future diagnostic information. The study of blood parameters has been carried out using standard test systems on an automatic veterinary biochemical analyzer. Different methods and terms of blood storage had a significant impact on the level of metabolites in the blood. The greatest deviations of indicators were recorded during storage of whole blood for more than a day at a temperature of + 4°C, as well as when it was frozen. Storage of blood serum at a temperature of + 4°C for no more than a day or its freezing did not lead to significant changes in the studied parameters. In production conditions, in case of difficulties in the rapid blood delivery to the main specialists of agricultural enterprises (when it takes more than a day), for greater stability of the content of analytes in the blood, we recommend separating the serum and freezing it with further transportation for the analytical stage of the study.