To organize rationed biologically valuable feeding of cows it is possible by the selection of such correlation of high-quality forage in rations, what would meet the physiology of animals feeding, gave an opportunity to the organism maximally to use nutrient substances on formation of products, maintenance of good  state of health during life. It is necessary to take into account that organic and mineral substances of forage, that are in the rations must take the deep chemical converting  in the organism of animals with obligatory participation of substances that stimulate and regulate these processes.

Such substances are proteins-enzymes, that accelerate chemical reactions in the organism in millions times and in the complement of that microelements and vitamins that enter with forage or with premixes. Absence of some microelements or vitamins leads to decrease of enzymes activity and resulted in metabolic disturbance in the organism of animal, worsening the state of animals health, decline of the productivity and reproductive ability. Zinc deficiency in rations reduces fecundity of dams, and protracted deficiency can result in their sterility.

The objective of the research was determining of optimum levels of mixed legade complex of Zinc in the combination of Copper, Cobalt, potassium iodide and sodium selenite in the feeding of highly productive cows in the first half of dry period.

To conduct investigation five groups of cows of Black-and-White dairy breed were chosen from “Agrosvit” Mironiv district, Kyiv Region. Difference in feeding of highly productive dry tested cows consisted only in that to the mixed fodder concentrate to the cows of the 1-st control group was entered sulfate of Zinc 795 g/t, that provided recommended norm in this element, and the cows of the 2-d tested group were provided with mixed legade complex of Zinc 895 g/t.

The mixed legade complex of Zinc, g/t was entered the cows of the tested groups: the 2-nd – 895, that provided a deficit on 100 %, the 3-d – 671, that provided a deficit only on 75 %, the 4 – th – 448, that provided a deficit on – 50 %, the 5-th – 224, that provided a deficit on 25 %. The cows of the 5-th tested group received only 25 % deficit of Copper, Cobalt, Iodine and Selenium. During 30 days of dry period, and in the first 100 days of lactation all tested cows received the same set of fodder. In the first 100 days of lactation the rations of tested cows differed in different amount of mixed fodder that was entered in rations calculating on 1 kg of milk yield.

After finishing of comparative period of the experiment the difference in feeding of the tested cows was absent but in the main period of experiment using different levels of mixed legade complex of Zinc affected different on eating forage. 

So, from set 4 kg of hay tested cows consumed 3,8–3,9 kg, or 95,0–97,5 %; from 18 kg of corn silage – 15,8–17,7 kg, or 87,8–98,3 %; from 8 kg of clover – 7,2–7,7 kg, or 90,0–96,3 %.

Consuming dry substances of fodder in the calculation 100 kg of live weight of cows resulted 2,1 kg in the 1-st control group and 2,15–2,23 kg in the tested groups. The cows from the 5-th tested group consumed dry substance the best due to best consuming of hey – by 2,6 %; silage – on 12,03 %; clover – on 6,94 % in compare with the control group. Consumed fodder supplied cows with raw protein on the level 14,2–14,33 % from dry substance of heavy soluble fraction on the level of 61 % of raw protein.         

Zinc supply was as follows: the 1-st control group 96,1 %, the 2-nd tested group 97,51 %, the 3-d tested group 86,0 %, the 4-th tested group 75 % and the 5-th tested group 64 % to the norm. Supplying of different levels and sources of  Zinc in the organisms of tested cows during the first 30 days of dry period directly depends on their live weight.   

Weighing of tested cows at the end of the first stage of dry period showed that their live weight was increased. This increasing in the cows of the control group was 24,8 kg and in the tested cows it was more by 1,2–16,5 % or 0,3–4,1 kg more. Difference was relible for the cows of the 4-th and the 5-th tested groups (Р<0,01–Р<0,001).

This difference in gaining of live weight of cows from the control and tested groups may be explained by less requirements of Zinc in this period.

In the second stage of dry period a tendency of live weight gaining was marked in the tested cows in spite of that the levels were the same.

Tested cows differed from control cows on data of live weight on the 3-d day after calving: animals from the tested groups exceeded the control one by 1,4–6,8 kg.  

Live weight of calves at birth increased by 2,7–8,7 % in the tested groups in compare with the control one.

Thus, obtained results show that supplying the organism of dry cows with different quantity of Zinc influenced as on live weight of cows as on live weight of calves at birth.   

Perspective of further investigations is studying the influence of mixed legade complex of Zinc in the rations of highly productive cows on the quality of colostrums, milk productivity and reproductive ability of cows.   

Key words: highly productive cows, premix, microelements, acid salts of microelements of Copper, Zinc and Cobalt, potassium iodine, sodium selenite, mixed legade complex of Zincm live weight.