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.

In the conditions of the Republic of Belarus there was studied the activity of hepatic specific enzymes of blood serum of bull calves of black-and-white breed in course of application of various doses of zinc-containing preparations. Application of zinc-containing preparations led to multidirectional change of activity of hepatic specific serum enzymes. Application of Zinkovet preparation in dose of 1,8 g/100 kg of live weight made it possible to essentially grade the indexes of hepatic tissue affect. In the experimental group at animals there was marked the lowering in activity alanine-aminotransferase, serum glutamic oxalacetic transaminase and gamma-glutamyl transpeptidase. At the same time, there was noted the increasing of zinc-containing enzymes activity (sorbitol dehydrogenase and glutamate dehydrogenase). All these processes were caused by zinc inclusion into the metabolic process.

In the conditions of the Republic of Belarus there was studied the influence of various doses of kizelgur on metabolic processes and natural resistance of poultry by an example of lying hens. Use of the mineral additive rendered the positive influence on protein, carbohydrate, lipidic and mineral metabolism in hens. It was marked that in blood the content there was an increasing of crude protein on 11,5-11,7% (Р less than 0,05), crude lipids - on 1,9-5,3%, glucose - on 25,1-54,6% (Р less than 0,01), calcium - on 0,8-12,4%, phosphorus - on 8,9-15,9%, iron - on 9,2-24,6% (Р less than 0,01) and magnesium - on 9,3-21,6%. The laying hens which were fed with the mineral kizelgur additive were characterized by better resistance reactions. Bactericidal activity of blood serum of the experimental hens was higher on 2,7-15,3% (Р less than 0,01), lysozymic activity - on 1,3 22,5% (Р less than 0,05).

In the conditions of the Republic of Belarus there was realized a comparative estimation of efficiency of the increased level of phosphorus, calcium, copper, zinc, cobalt, iodine and vitamins A and D in comparison with regulations of the All-Union Academy of Agricultural Sciences of the Soviet Union (1985) and the Russian Academy of Agricultural Sciences (2003) for pregnant cows in a dry period at summer feeding. Also, there was studied the digestibility of nutritive substances of forages in cow diets, as well as the evaluation of their after-effect on revelation of dairy productivity indexes in the subsequent two months of lactation, biochemical blood indexes and payment of forage byproducts. As a result of application of moderately increasing levels of macro- and trace elements, vitamin D, and phosphorus in particular on 10,0% in comparison with 15,0% and existing level in rations of pregnant cows there was stated a slight decreasing of pregnancy duration of animals on 0,10 day. Also, there was marked an increasing of milk yield of milk with 4% fat content on 1,64% and 4,48%, the growth and development of calves in the prophylactic period on 4,18 and 4,61%,; and the was an improvement of organic substance digestibility on 1,52 and 1,78%. Besides, there was revealed more moderate number of leukocytes and content of crude protein.