The effectiveness of the use of mixed ligand complexes of Zinc, Manganese and Cobalt in the diets of high-yielding cows in the final period of lactation, and their effect on productivity, nutrients digestibility and nitrogen metabolism in the animals’ body was studied in a scientific economic experiment conducted at the Terezyne Ltd. of Bila Tserkva district, Kyiv region. Five groups of highly productive cows of Holstein, Ukrainian red-spotted and Ukrainian black-spotted dairy breeds were selected on the principle of analogues. The difference in feeding cows of the groups was in the following: - the diet of the control 1st group was balanced to the norm only with trace elements of Selenium, Copper and Iodine. - cows of the 2nd and 3d experimental group were fed with the norm of all trace elements (for the 2nd experimental groupthe norm was provided due to introducing sulfates of Zinc, Manganese, Cobalt, Copper, Selenium Suplex and Potassium iodide; for the 3d experimental group , sulfates of Zinc, Manganese and Cobalt were substituted with their mixed ligand complexes). - for cows of 4th experimental group, the concentration of Zinc, Manganese and Cobalt in 1 kg of dry matter feed was reduced by 11% compared to the group 3. - for the 5thgroup it was 22% lower than in the group 3. The results of the studies show that the use different doses of mixed ligand complexes of Zinc, Manganese, Cobalt in cows feeding with the use of Selenium Suplex, Copper sulfate and Potassium iodide during the final 100 days of lactation did not affect milk productivity. Each cow of the control group in the final period of lactation yielded 2220 kg of natural milk, whereas the cows of the experimental groups 2-5 yielded 40-120 kg more. The difference in the average daily milk yield of 4% fat was 0.5–1.91 kg, and this difference was significant (p <0.001). The results of the balance experiment show that the experimental groups animals digested feed nutrients and absorbed Nitrogen better. Nitrogen was deposited in the body of cows of experimental groups 2, 3, 4 and 5 by 2.1 g, 4.1, 7.3 and 12.8 g, respectively (p <0.05) in comparison with the control group, which provided milk productivity increase and reduce the need for these elements.The use of mixed ligand complexes of Zinc, Manganese and Cobalt contributes to milk productivity increase through reducing feed costs per 1 kg of product and reduces the need for these elements. The best performance results were obtained in the experimental group 5, where the animals were fed with the feed containing 1 kg of dry matter, mg: Zinc 35, Manganese 35; Cobalt 0.4; Selenium 0.3; Copper 9 and Iodine 0.8. 

Key words: cows, Zinc, Manganese, Cobalt, Copper, Selenium Suplex, Potassium iodide, mixed ligand complexes, Nitrogen balance