The increase in milk production of specialized dairy farms and complexes are directly depended on full value of animal nutrition and feed quality. However, in their publications scholars and practitioners note that with increasing of milk production due to import herd of Holstein breed in Ukraine, there is a tendency to reduce the duration of their productive use. This is because the Holstein breed is improving and it needs a high level of feeding not only essential nutrients, as well as biologically active, especially micronutrients.

Microelements (Ferrum, Copper, Zinc, Manganese, Cobalt, Iodine, Selenium and others like that) belong to the bioactivators, "regulators" of life – enzymes, hormones, vitamins (В₁₂). The deficit of microelements, as well as vitamins, reduces the use of feed protein, common consumption of forage also diminishes. Connections of microelements, that are used in animals feeding must be easily digested and effectively used by an animal organism.

The objective of our research was determination of optimal doses of mixed ligand complex of Cobalt in combination with the sulfates of Zinc, Copper and selenite of nitrogen in feeding of highly productive cows in dry period and in the first 100 days of lactation, and to determine their influence on the indexes of blood, because processes that take place in an organism largely affect quality composition of blood, and it is relatively permanent index of  estimation of metabolism and the state of cows’ health.

Feeding of experimental cows in preparatory and experience periods was conducted after identical rations. A difference in feeding consisted in that in an experience period, during a 60 twenty-four hours of period of dry period and on the periods of lactation the cows of control group were fed with premixes of preparatory period, in composition of that there was mixed-ligand complex of Cobalt, sulfates of Zinc, Copper and selenite of nitrogen the doses of that covered a deficit in Cobalt, Zinc and Copper on 100 % and Selenium 0.3 mg/kg.

Doses of mixed-ligand complex of Cobalt were added to the cows of tested groups in the mixed fodder concentrate which covered deficiency in this element on 85, 70, 55 and 40 %.

Given data specify that in blood of cows of the German selection, the mixed-ligand complex of Cobalt was fed that, the level of red blood little bodies in an absolute value was more on 0.08–0.73 Т/l for the cows of experience groups comparatively with a control group, that in a percentage ratio is 1.0–8.8 % (Р>0.05). Thus for experience cows the substantial increase of degree of satiation of red corpuscles is marked by hemoglobin.

According to this hematology criterion animals from the 2nd experimental group dominate cows from the 1st control group on 5.7 g / l or 5.1 %, 3rd – 11.4 g/ l or 10.1 %, 4th – 7.9 g / l or 7.0 % and 5th – 8.4 g / l or 7.5 % difference between groups is highly possible (P<0.01). The concentration of total protein in the blood of dairy cows from research groups to control increases in 1.4–4.7 g / l. Percentage difference is 1.79–6.0 %, and according to the statistics is significantly (P<0.01) for the 3rd and 4th experimental groups compared to the 1st control group.

In the blood of cows from the 2-nd, 3-d, 4-th and 5-th research groups it was noted the increase of albumin, respectively, 4.8 %; 11.9 % (P<0.001); 7.85 % (P<0.001) and 3.75 %; α-globulin – 4.1 %; 8.2 % (P<0.001); 2.74 % and 1.37 %, and γ-globulins, respectively, 3.29 %; 9.86 % (P<0.001); 5.6 % (P<0.001) and 3.29 %. The concentration of β-globulins in blood of cows from the 2-nd, 3-d, 4-th and 5-th groups was on 4.88; 2.38; 3.61 and 3.61 % lower compared to the control.

One of the factors that confirm it is content of Nitrogen, it’s concentration in blood of animals of experience groups prevails control on 0.4–0.36 mmol/l, that in percent equals 1.2–10.9 % (Р<0.001). Advantage of general Nitrogen of the 2-nd experience group above control presented 34.0 mmol/l or 1.79 % the 3-d – on 80.3 mmol/l or 4.24 %, 4th – on 44.3 mmol/l or 2.35 % 5th – on 36,4 mmol/l, or 1.92 % (Р<0.05). As for the concentration of protein Nitrogen in blood of cows of experience groups, a difference on this hematological index in behalf on experience groups against control folds 33.3–79.0 mmol/l, that in percents equals 1.79–4.26 % (Р<0.05). The amount of remaining Nitrogen in blood of cows of experience groups prevails the analogical criterion of control group on 0.6–1.3 mmol/l, or in percent expression on 1.52–3.30 %.

As for such hematological index as urea, it’s content in the cows of an experience group is lower comparatively with control on 0.08–0.55 mmol/l, or 2.1–16.6 % (Р<0.001).

Thus, the correction of mixed-ligand complex of Cobalt to the experimental highly productive cows of Holstein breed of the German origin activates motion of the synthetic processes in their blood that positively influences on digestion of proteins and shows antagonism to Zinc.

Key words: highly productive cows, premix, microelements, salts, Copper, Zink, Manganese, mixed-ligand complex of Cobalt, protein, albumins, globulins.