This article describes the effect of pre- and probiotics on the condition of intestinal microflora for newborn calves. It has been established that in the intestines of calves, in addition to lactic and bifidobacteria, conditionally pathogenic bacteria such as E. coli, staphylococcus and streptococcus are contained. When taking pre- and probiotics in the experimental groups of animals, a decrease in the content of conditionally pathogenic microflora was observed with a dynamic increase in obligate, which indicates a positive effect on the formation of intestinal microbiocenosis during the milk period.