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 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.

In the conditions of the Republic of Belarus there was studied the influence of high degree of cow productivity on the course of down-lying and state of endocrine status of animals and their reproductive qualities. Application of veterinary preparations Katozal and Ovoton made it possible to control the functional activity of cow dam and ovary providing the increasing of cow reproduction qualities. Results of tests of estradiol-17 beta and progesterone in blood serum of experimental and control groups cows were presented. Application of Katozal and Ovoton veterinary drugs made it possible to cause heat and insemination of 86,5-91,3% of cows. At the same time, according to the results of the first insemination the highest results were obtained at cows with low productivity indexes – 60,9% and according to productivity increasing this index lowered up to 32,7% and 29,8%, respectively. According to the results of all insemination in cases of 3500-5000 kg productivity only 2 cows (8,7%) were nonbearing.