The experiment was conducted on 16 Red-and-White cows in a 2 x 2 Latin square design with two levels of CaFA salts (with and without 6% CaFA salts in DM) and a high or low level of copper (13 vs 61 mg Cu/kg DM). The cows were fed grass and maize silages and a concentrate in the amount of 0.28 kg/kg of milk yield. DM intake of all of the cows averaged 16.8±0.1 kg, including 10.6±0.1 kg of silages at an intake of 6.2±0.1 kg d^-1 concentrate. Average FCM was 22.8±0.5 kg d^-1, with a content of 4.1±0.4% fat, 3.0±0.3% protein and 5.4±0.3% lactose. A significant negative effect of copper on the fat content of milk was found, whereas the effect of CaFA on daily fat and protein synthesis was positive. The total cholesterol content in milk was 13.6±0.4 mg/100 g and did not differ significantly for either of the experimental factors. No effect of the experimental factors was found on the Ca, P, Mg, and Zn contents in cow's milk, whereas a significant increase in the Cu level was observed. Feeding cows CaFA salts significantly lowered the content of saturated fatty acids in milk, i.e. of caprinic (C10), lauric (C12), myristic (C14) and palmitic (C16) acids, and increased the content of stearic and α-linolenic (C18:3, n-3) acids. The higher copper level significantly elevated the oleic acid (C 18:1) content of milk. CaFA salts led to a highly significant rise in the level of unsaturated fatty acids in milk; the high copper level increased them significantly. The concentration of acids having a cholesterol-lowering effect increased by 40.9 to 46.8% in response to CaFA salts and by 43.1 to 44.6% under the influence of copper. No significant differences were found in the glucose, total protein, urea and total cholesterol and HDL levels in the blood plasma of cows. Increased doses of copper lowered the level of LDL cholesterol and increased the plasma activity of aspartate aminotransferase and lactate dehydrogenase. Higher dose of CaFA salts significantly increased the plasma activity of alkaline phosphatase and copper level. No effect of the studied factors was found on plasma calcium, phosphorous, magnesium or zinc levels.