Promising direction in ensuring food security and independence of Russia is the widespread use and study of new feed additives of probiotic action. Today, probiotic preparations are widely used in dairy farming. They support the positive microbial balance of the gastrointestinal tract and stimulate the activity of the digestive, motor-evacuation, hormonal and immune systems. Authors studied the efficiency of the composition of 2 strains of Bacillus subtilis during 14 days after calving (1 experimental group) and 14 days before calving and 14 days after calving (2 experimental group) in the technology of milk production and improving its quality. In the process of conducting scientific and industrial experience, modern research methods were used that were able to obtain high-quality and most informative data on the processes occurring in the body. Analysis of the results of hematological blood parameters of animals of all groups confirmed the physiological of recovery of the cow's body in the postpartum period, but with different degrees of intensity. Animals of the experimental groups reached peak milk production. By the end of the third month in group 1, milk productivity was 28.94±6.84 kg, in group 2 - 32.17±3.33 kg, which formed an increase of 6.44% and 15.59% relative to the background values. In the control group of cows-27.90±7.25 kg. By day 150, the average daily milk yield in animals of the first group was 25.07 ± 4.38 kg, the second - 25.33 ± 2.52 kg, control 22.75 ± 8.82 kg. Milk quality indicators - fat and protein content in animals receiving probiotic supplements were variable. In the milk of animals of the 1st and 2nd groups, the average fat content was recorded 3.69 g / 100g and 3.74 g / 100g, respectively, and the average protein content was 3.104 g / 100 g and 3.240 g / 100 g. In peers of the control group, the fat and protein content in milk was determined to be 3.79 g / 100 g and 3.016 g / 100 g. The studies established and proved the promise of the widespread introduction of probiotic in dairy cattle breeding, which was based on the composition of endo- and exometabolites of 2 strains of Bacillus subtilis. There was an improvement in the physiological status and an increase in the milk productivity of Holstein cows of the black-motley breed.