The aim of our experiment was to compare the effect of different levels of the addition ofSaccharomyces cerevisiae (S. c.)yeast culture on feed carrier to the current ration MK DOJ Levucell SC 20, Saccharomyces cerevisiae CNCM I-1077 (E 1711) 20.1010CFU on the blood parameters of high-pregnant breeding cows and their calves. The experiment included 42 breeding cows of the Czech Fleckvieh cattle breed and their calves. The breeding cows were divided into two age groups, each of 21 heads. The first group included heifers and the second group consisted of cows on the 2ndand higher lactation. Each age group had 7 control animals (Heifers/Cows – control), 7 animals receiving 50 g of yeast culture on the feed carrier per head and day (Heifers/Cows – 50 g), and 7 animals receiving 150 g of yeast culture on the feed carrier per head and day (Heifers/Cows – 150 g). Blood of the animals was sampled three times during the experiment – two times in the cows and one time in their calves. The first blood sample was taken from the breeding cows before the start of feeding the yeast culture ca. 23 days before the expected parturition (Cow −23). The second blood sample was taken from the breeding cows within 24 hours after birth (Cow +2) and the third blood sample was taken from the calves on the 3rd–4thday after birth (Calf +4). Parameters ascertained in the processed serum were: immunoglobulines G (IgG), crude protein (CP), gamma glutamyl-transferase (GGT), urea, glutamate-pyruvate-transaminase (GPT) and glutamate-oxaloacetate-transaminase (GOT). Results of our experiment, which lasted from 16.3 to 28.6 (105 days) showed IgG in the serum of cows on the 2ndand higher lactation in the control group (3.8 ± 1.48 mg/ml) was statistically significantly lower (P < 0.05) in the blood sample Cow +2 than in the serum of cows in the 2ndand higher lactation fed with the lower concentration ofSaccharomyces cerevisiaeat the same sampling (15.9 ± 11.41 mg/ml). This correlates also with the fact that the content of IgG antibodies in the serum of calves after the cows on the 2ndand higher lactation in the control group (3.9 ± 2.06 mg/ml) was statistically significantly (P < 0.05) lower than that of calves after the cows on the 2ndand higher lactation with the lower concentration ofSaccharomyces cerevisiae(14.6 ± 8.67 mg/ ml).As to the higher addition, no statistically significant difference of the effect on the IgG content was recorded (P < 0.05).