PHYSIOLOGICAL PARAMETERS OF INTRAVASCULAR PROPERTIES OF PLATELETS OF HOLSTEIN CALVES DURING THE PHASE OF MILK FEEDING
There is reason to believe that in cattle of different breeds, there are differences in the level of platelet activity. The work was performed on 48 purebred milkman calves in Holstein breed. During the study, biochemical, hematological and statistical research methods were applied. During observation in the blood of calves, the number of discocytes increased slightly. The total number of active platelets for them during the phase of milk supply decreased by 20.0%, and the levels of platelet aggregates circulating in the blood of small and large sizes decreased by 20.0% and 40.0%, respectively. This was accompanied by a weakening of the synthesis of thromboxane in their platelets, a decrease in the amount of adenosine phosphate in them, and a weakening of its secretion. It is clear that Holstein calves in the phase of milk nutrition are characterized by a high functional perfection of the hemostatic properties of platelets. This provides them with physiologically very favorable conditions for microcirculation in their tissues. This is ensured in them by a certain weakening of the activity of mechanisms providing platelet aggregation and secretion processes. It is clear that the low intravascular activity of platelets in calves of the Holstein breed during the milk feeding phase forms the optimum of perfusion and metabolism in all their tissues, which is extremely important for the rapid growth, development and creation of the foundations for the future high productivity of this breed of cattle.