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 analyzed the influence of the following paratypical factors on cow productive longevity: age of the first calving; milk yield at the first lactation; and a birth season. At the experimental animals there studied the indices of dairy efficiency: a lifelong milk yield (kg); a lifelong yield of dairy fat (kg); the total duration of the lactation period (days); duration of practical use (lactations). There was noted a tendency of increasing of a term of productive use and lifelong productive efficiency at the animals the practical economic use of which was begun in later terms. The insemination of these animals was approximately realized at the age older than 21 months. Also it was stated that in accordance with all investigated indices (except for a milk yield per one day of lactation) the highest indexes were typical for cows which had the least milk yield at the first lactation.

In the conditions of the Republic of Belarus there was analyzed the efficiency of administration of nonconventional feed materials in diets of highly productive cows and its influence of indexes of natural resistance at different physiological stages of animals. In the process of studying of adaptation processes of highly productive cows at different stages of lactation it was determined that feeding with nonconventional melanoidin-humic additives at different physiological periods rendered a positive influence of highly productive cows, promoted the increasing of natural resistance of animals and improvement of immuno-humoral blood indexes. Administration of an additive Ehkolin in a ration of highly productive cows with stimulation for increasing milk flow in a dose of 100 ml per head promoted the increasing of blood serum bactericidal activity on 5,2%, beta-lysine activity - on 7,2%. Feeding of animals at a basic lactation period with 50 ml of preparation Ehkolin-2 provided the maximum increasing of lysozyme activity of blood serum (on 6,2%) and beta-lysine activity of blood serum (on 12,7%), and also promoted the activation of leukocytopoiesis. Addition of Ehkolin-3 in ration structure of dry cows in a dose of 750 ml increased the indexes of lysozyme activity of blood serum on 7-8,6%, bactericidal activity of blood serum - on 2,2-3,6% and beta-lysine activity of blood serum - on 2,2-3,6%.

In the conditions of the Republic of Belarus annually in 25-50% of total number cattle there was stated ketosis (milk fever); as a result, from each cow in cattle breeding farms receive less milk per lactation on 10-15%, as well as there is a lowering of fat and protein (and biological value) content in milk. In course of the study there was analyzed the influence of mineral and energy supplement Felutsen K-1-2 for the preventive treatment of ketosis of highly productive cows. Research results showed that application of the analyzed additive rendered the positive influence on morphological and biochemical blood indexes. In particular, there was an increasing of hemoglobin level, content of total protein, albumins, magnesium, calcium, and phosphorous. It also rendered positive influence on lipid exchange. In course of the study it was marked, that the prophylactic efficacy of mineral and energy supplement Felutsen K-1-2 in the experimental groups was 100%, and the control one – 80%.

In the conditions of the Republic of Belarus there was studied the preventive efficiency of various forms of a complex additive Felutsen against polymicroelementoses of calf-bearing dry cows and its influence on some of biochemical blood indexes. Research results proved high prophylactic efficacy of various forms of the additive Felutsen against polyhypomicroelementoses of calf-bearing dry cows. Restoration of a microelement homeostasis of cows made it possible to normalize the functional activity of liver, to prevent development renal insufficiency and dystrophic changes in bone tissue. The most expressed metabolic changes in blood of calf-bearing dry cows were stated after application of the carbohydrate-mineral additive Felutsen-briquette universal. There was given the analysis of structure of studied forms of complex additive Felutsen; indexes of trace element metabolism in cows; indexes of protein metabolism and level of nonprotein nitrogen; indexes of blood characterizing the functional condition of liver and carbohydrate metabolism of cows; indexes of trace element metabolism in cows after the termination of application of the additive.

In the conditions of the Republic of Belarus there was analyzed the metabolic status of cows in the finishing period of pregnancy, as well as influence of its disorders on clinical status and breeding and economic indexes of new-born calves. Research results showed in pregnant cows in interlactation period there was stated the development of subclinical poly-hyper trace element deficiencies. There was realized the analysis of indexes of trace elements metabolism in cow blood; blood indexes characterizing protein metabolism; as well as biochemical blood indexes characterizing the carbohydrate metabolism and functional state of liver and kidneys. In the conditions of subclinical poly-hyper trace element deficiencies of cows there were revealed the biochemical changes which showed the lowering of the functional activity of liver and intoxication. Economic and clinical indexes of calf crop were analyzed. Research results showed that in calves (obtained from cows with trace element deficiencies) in an early extrauterine life there statedthe development of a toxic form of dyspeptic disorder which was accompanied with high degree of young stock death.

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 efficiency of application of national mineral additives (mineral feed additive produced on the basis of dolomitic meal) in rations of milking cows. In course of the study there were analyzed physical and chemical blood indexes; hematological indexes of cows; biochemical blood indexes; mineral composition of blood; natural resistance of cows. As a result of the realized study it was established, that an optimum dose of a dolomitic meal for milking cows during the winter period was 0,3% per dry matter of a diet. There was proved the possibility of increasing of a daily average milk yield of cows on 11,7%, fat and protein content in milk - on 0,04 - 0,06%, as well as lowering of quantity of somatic cells on 13,6%. Application of a national mineral additive rendered the positive influence on blood indices to what that was proved by increasing of erythrocytes (on 10,9%), thrombocytes (on 5,4%), haemoglobin (on 6,5%), crude protein (on 10,6%), and also macro- and trace elements. Introduction of a dolomitic meal into cow diets made it possible to increase the indices of natural resistance of cows on 0,5 - 4,0%.

In the conditions of the Republic of Belarus there was realized a comparative study of meat productivity of mongrel Gereford х black-and-white heifers ad purebred black-and-white heifers in the conditions of different levels of concentrated feedstuff in cattle diets; and determine the most efficient and long-term method of animal breeding for meat. Research results showed that breeding of meaty of hybrids of Gereford х black-and-white heifers of the second generation without using the feeding concentrates in their diets or on using rations with a low rate of feeding concentrates (10-20%) proved to be more effective, than breeding of purebred black-and-white herdmates (for which specific density of the concentrated forages in diets made up 20% through pregnancy). Hybrids on Gereford breed in accordance with meat productivity level surpassed the purebred black-and-white animals. The most considerable results were marked at hybrid heifers with relative density of concentrates in a ration of 20% which in accordance with slaughter weight indexes surpassed the herdmates of black-and-white breed on 39,1 kg or on 23,68%, in accordance with slaughter yield - on 8,2%, in accordance with fresh carcass weight - on 37,9 kg or on 23,8%, in accordance with weight of inner porc - on 1,19 kg or on 20,62%.

In the conditions of the Republic of Belarus there was realized a comparative study of peculiar features of influence of combined application of Khelavit preparation and protein-vitamin-mineral feed supplements Khendriks and Spaeta-kontsentrat on health status of cows and quality of obtained cow milk after application of these preparation for the preventive treatment of osteodystrophy. In course of study there were analyzed haematologic and biochemical blood indexes of cows after application of the experimental preparations. Results of physical and chemical indexes of milk were presented. Research results showed that the analyzed protein, vitamin and mineral feed supplements caused the normalization of biochemical blood indexes in comparison with animal of a control group. Besides, application of mentioned above drugs promoted the increasing of veterinary and sanitary quality and technological properties of produced milk.