EN
The aim of the study was to verify the assumption that adding chelates, vitamins and yeasts to the winter diet of cows, at the end of pregnancy and at the beginning of lactation, increases milk production and affects the serum concentration of lipids. The experiment was performed on three groups of HF cows (a total of 60 heads) in their second or third lactation, fed a balanced diet based on maize silage, grass silage and haylage (56% dry matter of the feed) and a concentrate (group 1 . control). Approximately 14 days before delivery and 120 days after delivery the diet of group 2 was supplemented with mineral components (chelate complexes Mg, Mn, Cu, Zn, Se ) and vitamins (E, PP, β-carotene). Group 3 received Yea Sacc1026 bioformula (containing Saccharomyces cerevisiae1026) in addition to its normal rations and supplements (as in group 2). Supplementing the cow.s winter ration with vitamins and minerals resulted in a significant increase in mean daily milk production during the first 120 days of lactation (from 23.98 kg to 25.18 kg) in comparison to the control group. This milk had higher concentrations of non-fat solids and crude protein (P ≤ 0.01), including the N fraction of true protein (P ≤ 0.05), as well as lactose and dry matter. Milk fat had the highest level of polyunsaturated fatty acids (on day 30 and 120 of lactation), including linoleic acid (C18:2), and a higher concentration (on the day 120 of lactation) of hypocholesterolemic acids (45.46 g/100g FA). Mineral-vitamin supplements shortened milk coagulation time (by 14%), and increased the alcohol number (from 2.28 to 2.81 ml 80% C2H5OH). Yeast (Yea Sacc1026) did not improve the effectiveness of chelates and vitamins added to the ration. The supplements tested in the study reduced the somatic cell count in milk (P ≤ 0.05). Vitamin-mineral supplements and yeasts increased (especially on day 120 of lactation) the serum levels of phospholipids and triacyloglycerols (chelates and vitamins) and total cholesterol (yeasts).