The article is devoted to the study of the role of the probiotic complex “LiquaFid” on the formation of a microbial community in the large intestine of sows and piglets at the lactation stage. The mechanism of action of probiotic strains is due to the antagonistic effect to a wide range of pathogenic microorganisms, pathogens of lung infections, infections of the gastrointestinal tract, in particular to pathogens of salmonellosis, as well as immunomodulatory effects on the body. In the course of the experiment, we studied the quantitative and qualitative composition of the microbial community in lactating sows and suckling piglets in the large intestine. The biomaterial was selected from clinically healthy animals. Fecal examination was carried out in the molecular genetic laboratory of the “BIOTROF” company by real-time PCR using special diagnostic kits for the study of the biocenosis of “Femoflor®”. During the work, he beneficial effect of the probiotic complex “LiquaFid” on the formation of the microbiota of the large intestine of both sows and suckling piglets was noted, namely, it was found that the total microbial mass in the experimental group of sows increased by 74%. Against the background of the use of probiotics, the number of representatives of pathogenic microflora in the large intestine in both groups of experimental animals decreased significantly, the most noticeable of which was a 3-fold reduction in representatives of Streptococcus spp. piglets of the experimental group are in the feces.