Platelets' functionality is important for the activity of hemostasis and metabolism in mammals such as cattle. They are of particular importance in the growth of livestock offsprings. 43 healthy calves belonging to the Dutch breed were observed. The evaluation of blood parameters was carried out in these calves at the age of 11, 15, 20, 25, and 30 days. During this time, calves showed some tendency to inhibition of platelet aggregation and a tendency to increase discoid platelets in their blood. This was accompanied in calves by a decrease in the blood of platelets that showed their hemostatic properties and the number of their dynamic aggregates of any size. These processes were associated in calves with a decrease in the synthesis of platelet thromboxane, a decrease in the amount of phosphated adenosine in their platelets. During the milk feeding phase, the number of contractile proteins in platelets of calves tended to decrease, with a tendency to a decrease in the severity of their additional synthesis under conditions of platelet aggregation. In purebred Dutch calves, during the phase of milk nutrition, a functional optimum of platelet activity is noted, which provides the basis for the most active microcirculation, providing all the conditions for the intensive development of their organs and tissues.