Physiological Properties of Platelets in Newborn Calves of the Kholmogory Breed

Abstract

The platelet activity in newborn calves of the Kholmogory breed was assessed. The studies were conducted on 39 animals obtained from healthy cows of 2–3 calving. Calves were examined five times in 2 days during the observation period. A tendency towards an increase in the activity of the aggregation process of blood platelets with all tested inducers was revealed during the neonatal phase. It was noted that the number of discoid platelets in the calf blood tended to decrease during the observation period. In these conditions, the level of activated platelets increased by 12.9% in total and the content of freely circulating aggregates of small, medium, and large sizes increased. These changes were provided in the calves by a slightly increased synthesis of thromboxane in blood platelets, which was due to the increased activity of platelet cyclooxygenase and thromboxane synthetase. In addition, a large role in the increase in platelet activity was played by growth in the quantitative content of adenosine phosphates in platelet granules and some increase in their secretion. The level of actin and myosin in calf discoid platelets during the neonatal phase increased by 6.4 and 12.6%, respectively. This was accompanied by a tendency towards growth in the amount of actin and myosin in platelets during their aggregation in response to a weak and strong inducer by 6.4 and 10.1%, respectively. The calves of the Kholmogory breed are characterized by a slightly increased activity of the hemostatic properties of platelets during the neonatal period, which eliminates their risk of bleeding under optimal conditions for microcirculation. The increasing intravascular platelet activity forms the conditions for optimal anabolic processes in tissues of animals in the neonatal period.