EN
The experiment was performed on 26 lactating Kamieniec breed ewes divided into two equal groups: I - control and II - experimental. Group II ewes were fed a diet supplemented with Saccharomyces cerevisiae dried yeast (Inter Yeast S), mixed with CJ concentrate, in the amount of 30 g/animal/d. Milk yield and the blood biochemical and haematological indices of ewes were determined on days 28 and 70 of lactation. Dietary supplementation with dried yeast caused a significant increase in milk yield (by 18.18% at the peak of lactation and by 15.53% towards the end of lactation). An increase in the counts of erythrocytes and leukocytes, haemoglobin concentration, and haematocrit values was observed in ewes fed a diet containing dried yeast. An increase in the concentrations of glucose and Na⁺ and Cl⁻ ions accompanied by a decrease in creatinine concentrations and a shift in the acid- base balance towards the alkaline side was demonstrated in the experimental ewes. Changes in the haematological parameters of experimental ewes were indicative of blood-supply improvement and immunity enhancement. Changes in biochemical indices suggested that the administered yeast supplement had a stimulating effect on energy metabolism and a protective effect on renal function, and that it contributed to preventing metabolic acidosis.