The formation and development of lactation function as an integral process of reproduction concerns all systems of the whole organism. The influence of heredity and expression of a trait under the influence of the environment determines the individuality and synergy of traits that determine milk productivity. Thermal conductivity, intracellular cyclosis, membrane potential, neuro-hormonal signals, blood and lymph are the main ways of communication and mutual influence of these signs. The nutrition system is most important for lactation function. Nutrients divided during digestion into amino acids, monosaccharides, fatty acids, and other elementary parts are delivered to the breast cells, where they become a substrate for the enzymatic synthesis of milk. Circadian changes in life processes and, first of all, feed intake reactions determine the circadian frequency of feed intake and the intake of nutrients into the organism. This affects the concentration of the intracellular substrate, the activity of enzymes and the thermal state of the whole organism. For life, as the highest form of existence of matter, thermal energy is particularly important. It not only connects the actions and interactions of all types of matter, it creates order from the chaotic movements of discrete heat sources, determining the measure of irreversible energy dissipation, entropy, and the gradient of changes in the metabolic processes of “outflow and inflow of energy”, the state of saturation and nutrient deficiency. The article is based on convergence, biophysical, ethological and animal sciences. Using the Joule as a single estimate of energy consumption and work performed (milk production) increases the scientific reliability of the research.