Investigation of acute and subchronic (chronic) toxicity of complexinates of trace elements in experiments with calves was realized in the conditions of the Republic of Belarus. The realized experiments were based on developed in Belarus veterinary preparations for the treatment and prevention of diseases connected with disorders of trace elements exchange containing chelate compounds of trace elements with sodium ethylene diamine acetate: Cuprovet (on the basis of CuNa); Cobalvet (on the basis of CoNa), Zinkovet (on the basis of ZnNa), and Feravet (on the basis of FeNa). There were the following indexes of ferrum in nephros - 55,3 +/- 2,26, in muscles - 134 +/- 26,6 mkg/g, and in liver - 565 +/- 35,5 mkg/g after administration of Feravet. There were the following index of zinc in nephros - 56,3 +/- 2,64, in muscles -25, 8 +/- 1,23 and in liver - 84,4 +/- 3,29 mkg/g after administration of Zinkovet. There were the following indexes of cuprum in nephros - 4,1 +/- 0,325, in muscles - 2,33 +/- 0,117, and in liver - 12,3 +/- 1,12 mkg/g after administration of Cuprovet. There were the following indexes of cobalt in nephros - 40,35 +/- 2,29, in muscles - 12,5 +/- 0,98, and in liver - 126,5 +/- 10,45 ng/g after administration of Cobalvet. Parameters of toxicity of all preparations were by the example of laboratory mice, rats and calves given. Content of trace elements in blood of calves in dynamics of the experiment was analyzed. There were determined parameters of acute toxicity of the analyzed preparations: they all could be referred to substance hazard category 4 (low-hazardous substances). The determined parameters of acute toxicity made it possible to recommend them for treatment and prophylaxis of microelementoses of cattle, as well as to use them as feed additives taking into consideration that defect action levels of the analysed preparations exceed the deficiency needs of cattle in case of their limited cumulation

Investigation of spreading of diseases of micronutrient deficiencies at cow breeding farms of Grodno district of the Republic of Belarus depending on the season and character of polymicroelementoses, as well as the determination of relations between polyhypomicroelementoses and state of new born calves were realized. Clinical investigation of 1350 milked and calf-bearing dry cows and biochemical analysis of 450 blood samples taken at nongrazing time (before cows pasture) and at pasture time were conducted. The following animal groups were selected: the first group – cows after calving; the second group – the cows of three month pregnancy; the third group – calf-bearing dry cows. The following groups were selected among calf-bearing dry cows in nongrazing and pasture time: clinically healthy cows, which had biochemical blood changes, showing development of subclinical polyhypomicroelementoses (n = 20); clinically healthy cows with blood indicators, standing in limits of physiological standards. Number of calves was considered after calving of cows of both groups. Body weight, realization of staying and sucking position, evidence of sucking reflex, and calves disposition to neonatal pathology were considered in the study. Research result showed that cow microelementoses were marked by the development of subclinical polyhypomicroelementoses. Among cow polyhypomicroelementoses there was noted the domination of states followed by lowering of zinc, cobalt and cuprum content. Polyhypomicroelementoses were developing both in winter housing season and in course of grazing season. Polyhypomicroelementoses involve cows of different physiological states and were spreading more intensively at cow dry period and after calving. Calves obtained from cows with polyhypomicroelementoses often had the state of hypotrophy and high incidence of dyspepsia at colostric period. Clinical and biochemical status of the analyzed calves was characterized by signs of intoxication and hepatic insufficiency