In the conditions of the Republic of Belarus there was studied the interrelation between content of major nutrient elements (calcium and phosphorous) and trace elements (iron, copper, cobalt, and manganese) in forages and blood of first-calf cows at the first and last stages of lactation. Also, there were developed formulas of mixed forages and a premix for these animals. The studies were realized at the Agricultural Production Co-operative Olgovskoe of Vitebsk region (Belarus). Research of analysis of forages and state of mineral metabolismat heifers made it possible to draw following conclusions: in cow rations there was marked the deficiency of vitamin D, as well as some trace elements (cobalt and manganese) in the conditions of calcium and phosphorus excess. In spite of a high content in a calcium in diets, it was noted than in blood plasma the concentration of this element was below the standard for the majority of animals. Lack of cobalt and manganese of whole blood of cows was connected with a low level of these elements in cow diets. The surplus contents of copper in forages and blood of animals against the background low activity of ceruloplasmin the weakened antioxidant defense of heifer cows. For preventive treatment of possible hypo trace element deficiencies and metabolic disorders of heifer cows at the final stage of lactation there can be recommended the correcting of cow diets with inclusion into their composition of the developed for compound of mixed fodder and premix.

In the conditions of the Republic of Belarus there was studied the influence of various doses of dolomite on productivity, egg quality and a mineral metabolism of laying hens. The research was realized by an example of laying hens of Highsex Brown. The experimental hens at the age of 250 days old were divided into 4 groups on 60 heads in each by means of analog method. Laying hens of the first (control) group were fed with a basic diet including 5% of a soya cake (cockle-shell), and hens of the second, third and fourth (experimental) groups instead of a soya cake were fed with a mixed fodder with addition of a mineral additive of dolomite. Hens of the second group were fed with the additive at a rate of 2%, the third group - 3%, and the fourth group - at a rate of 5% of weight of dry matter of forage. During the experiments there were maintained optimum parameters of microclimate, recommended temperature and light regimes and a sufficient ultra-violet irradiation. As a result of the realized research it was established, that use of the mineral dolomite additive in feeding of laying hens proved to be possible as a substitute of an expensive import cockleshell. Use of various doses of dolomite promoted improvement of mineral metabolism, increasing of productivity and improvement of egg quality of laying hens.

The given research results of feeding highly productive cows with new forage supplement of humic-melanoidine nature during the milking period show stable mineral metabolism, correction of their redundant supply within the diet, perfection of digestion and transition into milk as well as minimizing consequences of metabolism intensification. Reception new forage supplement promoted improvement of mastering by an animals organism of necessary iron during the given physiological period, to restriction of mastering of the microelements equal to the category of heavy metals

In the conditions of biogeochemical zone of the Republic of Belarus the most important role in mineral metabolism is played by such major mineral elements as calcium, magnesium, phosphorus, potassium and trace elements - cobalt, cupper, iron, iodine, zinc, manganese, and selenium. Based on the above there was determined the interrelation between the content of these minerals in fodder and blood of milking and dry pregnant cows. As a result of realized study it was found out that the content of major mineral elements and trace elements in fodder did not always correspond to their level in blood. In the conditions of insufficient supply of Ca, F, Mg, K, Fe, Си and Co in cow diets, the level of potassium in blood was lower standard and the other analysed minerals were within the standard limits. There was stated the direct correlation relationship between the level of some biochemical indices and content of mineral substances in cow diets. Positive correlation was stated between the content of calcium and magnesium and cholesterin level in blood