The aim of the study was to determine the effect of EM Bokashi® on selected parameters of the specific and nonspecific immune response of sows by in colostrum and milk samples. The percentage of cells with expression of CD19+, CD5+CD19+, CD21+, SWC3a (macrophage/monocyte), and CD11b+ molecules on the monocytes and granulocytes as well as the concentrations of lysozyme and acute phase proteins — serum amyloid-A (SAA) and haptoglobin (Hp) were evaluated. The study was carried out on a commercial pig farm, including 150 sows (Polish Large White × Polish Landrace) at the age of 2–4 years. Sixty female sows were divided into two groups: I — control and II — experimental. For the experimental group, a probiotic in the form of the preparation EM Bokashi® in the amount of 10 kg/tonne of feed was added to the basal feed from mating to weaning. The material for the study consisted of colostrum and milk. The samples were collected from all sows at 0, 24, 48, 72, 96, 120, 144, and 168 h after parturition. The study showed that exposure of the pregnant sow to the probiotic microbes contained in EM Bokashi® significantly affects the immunological quality of the colostrum and milk and caused an increase in the percentage of the subpopulations of B cells with CD19+, CD21+, and CD5+CD19+ expression in the colostrum and milk, which demonstrates an increase in the protective potential of colostrum and indicates stimulation of humoral immune mechanisms that protect the sow and the piglets against infections.