Use of mixed ligand complexes of Zinc, Manganese and Cobalt in feeding highly productive cows during the late dry period

The results of establishing the optimal feeding doses of Zinc, Manganese, and Cobalt in the form of their mixed-ligand complexes for high-yielding cows of Holstein, Ukrainian Red-Spotted and Ukrainian Black-Spotted dairy breeds during the late dry period were presented, their influence on the future productivity and reproductive qualities of cows were also determined. It was found that lower doses of mixed-ligand complexes of Zinc, Manganese, and Cobalt in the feed mixture stimulated its consumption better. The cows of the 4th experimental group consumed more of the feed mixture, where the concentration of Zinc and Manganese was 35 mg, and Cobalt – 0.49 mg per 1 kg of DM. At various doses of mixed-ligand complexes of Zinc, Manganese, and Cobalt, the increase in live weight in cows of the control group was 24.3 kg, and in the experimental groups, it ranged from 23.7 kg to 26.9 kg, which is 8.6% and 10.7% (P < 0,05) more in the 3rd and 4th groups compared with the control. A decrease in the concentration of mixed-ligand complexes of Zinc, Manganese, and Cobalt in the diets of dry cows in the experimental groups by 10, 20, 30 and 40% had a positive effect on their further milk productivity. During the first 100 days of lactation, they milked 60-180 kg of milk more compared to the control with an increase in fat content by 0.01–0.05%. Also, in the milk of experimental group’s cows, compared with the control, the protein content increased (3.22–3.23% versus 3.14%), and the feed costs per 1 kg of milk in them were lower by 3.5–9.4%. Smaller doses of zinc, manganese, and cobalt contributed better to lengthening the period of prolonged action of their mixed-ligand complexes on the body of lactating cows. The calves’ live weight at the birth in the 4th experimental group exceeded the indicator of their peers from the control group by 2.3 kg or 8.81%, while the calves obtained from cows of the 2nd experimental group prevailed the control by 1.6 kg, or 6, 13 %, from the 3rd experimental group – by 1.8 kg, or 6.90%, and the 4th experimental group – by 1.7 kg, or 6.51%. The duration of the service period in all experimental groups of cows was within the recommended norms and was 87.8 days in the control group, and the 2nd, 3rd, 4th and 5th experimental groups, respectively 84.7 days, 82.2; 80.6 and 83.5 days, respectively, and there was less in control by 3.1–7.1 days or 3.3–8.2%. The insemination index in the cows’ control group was 1.5, and in the experimental one – 1.2–1.4, which is 6.7–20.0% less.