Physiological responses of <em>Piaractus brachypomus</em> supplemented with ascorbic acid and subjected to hypoxia stress

Abstract

<p>Juveniles of <em>Piaractus brachypomus</em> (30 ± 4.76 g) were fed <em>ad libitum</em> for 30 days with a diet of 32% protein, supplemented with six different amounts of ascorbic acid (AA): t1 = 0 mg/kg; t2 = 100 mg/kg; t3 = 200 mg/kg; t4 = 400 mg/kg; t5 = 800 mg/kg; t6 = 1600 mg/kg. After the feeding phase, the animals had air exposure for 60 seconds and then returned to the water. Blood was collected by puncture of the caudal vein from three individuals per treatment at 5, 30, 60, and 360 minutes after being returned to the water. With these samples, concentrations of cortisol, glucose, lactate, and total proteins were determined in plasma. In serum, the concentration of Cl- and Na+ ions was measured. Finally, survival was calculated. Data were subjected to ANOVA variance analysis, and when differences were found, the means were compared using Tukey’s test (α = 0.05). Cortisol presented the highest peak in specimens fed with AA-free diet. Glucose concentrations were lower in fish supplemented with 400 mg/kg at 5, 30, and 60 minutes. Concentrations of the two ions remained stable over time in the specimens supplemented with 200 mg/kg. Survival was 100% in all treatments. Supplementation with AA concentrations between 100 and 400 mg/kg improved the response of animals to hypoxia stress</p>