Blood plasma antioxidants and dehydration in three-month-long trained Standardbred trotters before and after an intensive race

The aim of the study was to determine the total antioxidant status in the plasma of horses - Standardbred trotters, exposed to extreme oxygen action during a race. The experiment was carried out on 10 two-year old horses - five stallions and five mares, after three-month-long initial training. On the experimental day, peripheral blood was sampled twice from the horses: at rest and after a race over 3200 m at a pace of 550 m/min. In the blood were assayed: blood platelet, white blood cell and red blood cell counts as well as haematocrit value and haemoglobin concentration. The obtained values were the basis for calculating plasma dehydration factor (Df). In the plasma was determined the antioxidative ability of plasma (AAP). For assays, a TAS (Total Antioxidant Status) analytical kit of Randox manufacture (UK) was used. In 8/10 horses, the AAP value underwent a reduction after the race. The statistical analysis revealed a significant decrease in AAP value in horses after completing the race (Pp = 0.0126). This difference correlates with the value of Df factor (R² = 0.304), which may mean that prolonged organism overloading with intensive oxygen work leads to progressive exhaustion of its antioxidative reserves and in consequence, after crossing the critical value, to development of oxygen stress. The largest decrease of AAP value occurred in the horses capable of performing the largest effort (ΔTAS = 0.20 ± 0.14 mol/dm³). These animals, i.e. three stallions and three mares, were characterised by a lower heartbeat rate and a lower respiration frequency at rest as well as by the capacity for quick regeneration of these parameters after the completed race.