The concentration of total lipids, lipid fractions and the quantitative and qualitative composition of plasma lipoproteins of calves fed a diet supplemented with the biopreparation Yea-Sacc¹⁰²⁶ were analyzed. Supplementation of the diet with yeast cultures from days 8 to 84 of life had a positive effect on lipid metabolism, especially when the calves received solid feeds. This was reflected not only by higher levels of triglycerides, cholesterol and non-esterified fatty acids (NEFA) in blood serum but also by lipoprotein fractions. The concentrations of very low density lipoproteins (VLDL) and triglycerides (TG) in this fraction were the lowest in calves aged 84 days. Higher values (8 vs 5%; 78 vs 70%, respectively) were, however, observed in group 2. The low density lipoprotein (LDL) concentrations were the highest in all animals on day 84 of life and constituted an average 25% of serum lipids. In experimental group 2, cholesterol represented 47% of LDL lipids and was higher (on average 11%) compared with the control group.