Application of protein, vitamin and mineral supplement in diets of 1-3 months old calves in rate of 5% per weight instead of a part of sunflower cake, containing rape, peas, lupin and vitamid on a basis of halites, phosphite, phosphate, sapropel and a mineral-vitamin preparation in structure of grain forage against winter rations on the basis of rich in herbs hay (5%), milk (68%), mixed fodder (20%), whole grain (7%), and also summer rations with grass and legume mixture (7%), hay (1%), milk (65%), mixed fodder (20%), integral grain (7%) makes it possible to receive daily average weight gain of calves at level 833-867 grams at expenses of forages for 1 centner of weight gain on 3,3-3,4 сentner of forage units. Introduction into rations of the protein, vitamin and mineral supplement on the basis of local protein and mineral raw materials in number of 10% per weight in structure of mixed fodder for calves at the age of 3-6 months old against the background of winter diets with haylage (28%), mixed fodder (64%), molasses (8%), as well as summer diets with grass and legume mixture (30%), mixed fodders (66%), molasses (4%) makes it possible to receive daily average weight gains of calves on 944-967grams at expenses of forages of 4,0-4,1 сentner of forage units. Feeding of 1-6 months old calves with mixed fodders with inclusion of 5-10% of protein, vitamin and mineral supplement per weight with grain high-protein crops against the background of winter and summer diets with a ratio of the deconjugate protein to the non deconjugate one - 65:35 (in control group - 71:29) instead of sunflower cake makes it possible to receive the daily average weight gain at the level of 900-927 grams at expenses of forages 3,7-3,8 сentner per forage unit. Cost of presented mixed fodders decreases on 14%, and the cost price per 1 centner gain - on 7-8%

Activity of amylolytic, proteolytic, and lipolytic enzymes in the content and mucosa of intestinal tract, alkaline phosphatase in mucosa of intestinal tract, as well as the determination of calcium and phosphorous concentration in gastro-intestinal tract of hens were analyzed in the conditions of the Republic of Belarus. Results of analysis of the obtained experiment results of laying hens of parental stock by influence of various vitamin-mineral additives were presented. The highest activity of amylolytic, proteolytic, and lipolytic enzymes in 170-330 days old laying hens of Belarus-9 cross was marked in small intestine. There was stated the decreasing of enzymatic activity in proportion to removal from a stomach. At the same time, activity of alkaline phosphatase decreasds. Activity of alkaline phosphatase, proteolytic and starch-reducing enzymes in a mucous membrane of a duodenal gut was a bit higher than in mucosae of jejunal. Lipolytic enzymes showed high degree activity in mucosae of jejunal. Enzymic activity in large bowel was low. Addition of iodine-containing preparation Kajod into hen layer diets increased the activity of alkaline phosphatase, of amylolytic, proteolytic, and lipolytic enzymes in intestines. Enzymic activity of mucous intestines at hens of breed Plimutrok in process of removal from stomach decreased. In course of the period from 240 to 330-days old age the activity of studied enzymes in hen intestines decreased. Replacement of mineral additive Cockleshell by Pikumin did not render negative influences on changes in digestive enzyme activity. In 170-days old laying hens of Belarus-9 crossbreed the calcium content increased from the stomach to the small intestine, and then decreased in thick department. In the 200-days old hens the calcium concentration in a stomach increased in both groups and gradually decreased in the department of small intestine, but in rectum its quantity increased in both groups. In the period of intensive egg-laying (280 days) the general calcium content in thin department of intestines was less than in the stomach, later it increased in cecum and decreased in rectum. By the end of the experiment (330 days) the concentration of calcium in control group decreased from the stomach to the beginning of thick department of intestines, but in rectum its quantity increased. In experimental group the calcium content increased from a stomach to cecums and then decreased in rectum. In distribution of inorganic phosphorus in gastrointestinal tract departments at hens of various age groups the tendency to increase in its quantity in small intestine and the beginning of thick department of intestines, and then to reduction in rectum was observed. And at hens receiving premix Ajdeko, the phosphorus content, since 200-day age, was higher, than at hens receiving the basic ration

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

Analysis of supply of first-calf heifer diets with the mineral substances and their blood level at the first period of lactation as well as the development of the optimal feed formula of the mineral premix which could make it possible to neutralize the possible deficit of nutritive elements was realized in the conditions of the Republic of Belarus. It was stated that in animal diets against the background of protein and carbon misbalance there was noted the deficit of a number of trace elements such as manganese, copper, cobalt and zinc. In spite of sufficient content of calcium and phosphorus in cow diets, their concentration in blood plasma in first-calf heifers did not correspond to standard criteria, that was probably caused by vitamin D deficiency in cow rations. There was marked a low level of zinc, cobalt and manganese in whole blood of the majority of cows. With the purpose of correction of the first-calf heifer rations and for the prevention of possible hypomicroelementoses there was developed the composition of premix taking into account the necessary of cow feeding standards