This paper presents the results of the study of low temperature effects of moderate stress intensity and the mineral premix "PMVS" on some indicators of calf defense abilities in postnatal ontogenesis to determine the parameters that can be used as a way of increasing the resistance and the defense abilities of animals to adverse environmental influences. The values obtained from the studied parameters show the change in the resistance of calves in the postnatal period. Thus, the increase of the biological value of the ration, by including the mineral premix "PMVS" and the application of the low temperature of a moderate stress intensity have led to an increased serum phagocytic activity, bactericidal activity and lysozyme activity throughout the experimental period. During the whole research period, the diurnal weight gain in the experimental group was 766 g. Maintenance of the organism’s homeostasis within optimal physiological limits is the main task of the animals physiology. Determination of the parameters of influence of the food and heat factors on homeostasis and calf development in postnatal ontogenesis allows to create favorable conditions that can facilitate the acceleration of the functional maturation of vital organs and systems, increase the organism’s resistance and adaptive abilities of the organism to the influence of stress factors and the realization of the genetic potential of animals.