EFFECTS OF HIGH BUT NON-TOXIC DIETARY INTAKE OF SELENIUM AND COPPER ON INDICES OF THE ANTIOXIDANT DEFENCE SYSTEM AND ON ACCUMULATION OF TRACE ELEMENTS IN CHICKS

Lohman Brown chickens with age from the 1st to 35th day received the food with high doses of selenium (Se1 mg/kg), copper (Cu100 mg/kg), or both elements (Se1 + Cu100). Live weight increase of all three experimental chicken groups was by 9.3, 12.9 and 8.1%, respectively, in comparison with the control. The concentration of selenium in the blood of the Se1 group chickens was by 45.5, in liver by 63.4 and in kidney by 19.7% higher that in organs of control group chickens. Selenium accumulation in organs of Se1 group chickens was highly correlated with increase of glutathionperoxidase activity in blood (r = 0.90) and in liver (r = 0.85) and with decrease of glutathione concentration in liver. In Cu100 group chickens, copper concentration increased by 11.7 in blood, in liver by 23.7, and in kidney by 19.9%. Together with more intensive excretion of glutathione from hepatocytes, copper concentration in bile increased by 17.7% compared to that in control group chickens. Also wing feathers participated in the regulation of copper homeostatic balance, as copper concentration in feathers increased by 66.7%. The concentration of malondialdehide in liver of chickens from all groups was similar (43.5–45.2 μmol·g-1 wet wt.), indicating that overload of selenium and copper did not cause profuse production of oxyradicals in the organism. Increased accumulation of selenium and copper in chickens influenced biochemical regulation of iron, zinc and cadmium deposition in liver, kidney, tibia and feather, changing the relations between Se and Fe, Se and Cd, Cu and Fe, Cu and Zn, and Cu and Cd concentrations. The analysis indicates increased tolerance of chicken to loads of selenium (1 mg/kg) and copper (100 mg/kg) doses.