Relevance. An actual approach to solving the problems of improving animal health and increasing productive indicators is the development of biologically active additives based on microbial consortiums of probiotic microorganisms that synthesize active metabolites that increase the selective benefits of the beneficial microflora of the gastrointestinal tract and its biological activity in the correction of microbiocenosis and metabolism.Methods. The object of research was 5%, 10%, 15%, 20%, 25% sugar beet molasses. When cultivating in molasses, probiotic microorganisms Clostridium thermocellulociticus, Ruminococcus olbus, Clostridium lochheadii and Bifidobacterium bifidum strain 1 were used. A daily culture of microorganisms was used for inoculation on a nutrient medium, which was standardized to 1 × 106 CFU/cm3.Results. It has been established that the number of probiotic microorganisms that are part of the culture liquid during the cultivation of Clostridium thermocellulociticus, Ruminococcus olbus, Clostridium lochheadii on the eighth day in a 15% molasses-based nutrient medium is 9.9 × 106 CFU/cm³. In studies during the cultivation of B. bifidum, a significant increase in the content of Histidine by 1.13 times, serine, leucine + isoleucine, methionine by 5.5–7.0 times, and other non-essential and conditionally essential amino acids was found, which indicates a significant activity of probiotic microorganisms in nutrient medium. A significant activity of the complex of microorganisms Clostridium thermocellulociticus, Ruminococcus olbus, Clostridium lochheadii was determined, an increase in amino acids was found: lysine and glycine by 3.39 times, leucine + isoleucine by 1.3 times, meteonine and valine by 2.36 times, proline by 7.5 times.