The aim of the study was to assess the gut microbiota and selected haematological and biochemical blood parameters of weaned piglets following dietary supplementation with a probiotic and vitamin C. the piglets were divided into a control group (group C) and an experimental group (group E), with 30 piglets in each group. All animals received the same feed ad libitum. The animals in the control group (group C) received feed with no added probiotic and vitamin C. the piglets in the experimental group (group E) were given a supplement containing a probiotic (Bacillus cereus 1×109 CFU/kg) in the amount of 1.5 g/piglet/day and vitamin c in the amount of 300 mg/piglet/day. The supplement was administered for 28 days. The total numbers of bacteria of the family Enterobacteriaceae and of the genus Lactobacillus were determined in faeces. The erythrocyte count, haemoglobin level, haematocrit, leukocyte count, and percentages of neutrophils and lymphocytes were determined in the blood. The biochemical analysis concerned the concentration of triacylglycerols, total cholesterol, and LDL and HDL cholesterol. In group E a significant decrease (P<0.01) in the total number of Enterobacteriaceae bacteria was observed in the faeces of the piglets, accompanied by an increase in the number of lactobacilli relative to group C. E. coli was found to predominate over other microorganisms. Salmonella choleraesuis bacteria were present in the faeces of both groups before administration of the supplement, but were not found after its use. The supplement with probiotic and vitamin C caused a significant increase in the erythrocyte, haemoglobin and haematocrit levels in the blood of the piglets and a significant decrease in the concentration of triacylglycerols, total cholesterol and LDL cholesterol.
