Effect of organic selenium supplementation on age- related antioxidant enzymes activities and on lipid peroxidation in heart muscle of broiler chickens

The effect of organic selenium feed supplements on the activities of antioxidant enzymes and on lipid peroxidation was investigated in the chicken heart muscle during fattening. The experiment was carried out on Ross 308 broiler chickens of both sexes, either on standard diet (control group, n = 30) or receiving organic selenium supplementation (Sel-Plex, Alltech) in the standard diet (experimental group, n = 30). After two, four and six weeks of fattening, 10 chickens from the control group and 10 chickens from the experimental group were sacrificed. In the heart muscles of the birds from both groups, the activities of glutathione peroxidase (GSH-Px), catalase (CAT), cooper zinc superoxide dismutase (Cu,Zn-SOD), manganese superoxide dismutase (Mn-SOD), reduced glutathione (GSH) and lipid peroxide (TBARS) were determined. After the fourth week of age, the chickens that had been given organic selenium supplementation displayed a significantly higher activity of GSH-Px (P<0.001), Cu,Zn-SOD (P<0.05), and of Mn-SOD (P<0.05) than the control group of the same age. During the experimental period, there were no statistically significant differences observed in CAT activity or in GSH and TBARS concentrations between the control and experimental groups (P>0.05). During fattening, age-related differences of antioxidant enzymatic activities and GSH and TBARS concentrations were obtained in the control and in the experimental group. After four weeks of age, a significant increase in GSH-Px (P<0.0001), Cu,ZnSOD (P<0.01) and Mn-SOD (P<0.0001) activities was obtained in the heart muscles of the experimental chickens. As the chickens grew older, at six weeks of age, significant increases in GSHPx (P<0.0001), Cu,Zn-SOD (P<0.0001), and in CAT (P<0.05) activities were obtained in the experimental group. Simultaneously, at six weeks of age, a significant decrease in Mn-SOD activity (P<0.01) and GSH concentration (P<0.01) in the heart muscles of experimental birds was recorded. During the fattening, significant increases in GSH-Px (P<0.001) and Mn-SOD (P<0.001) activities were obtained in the control group after four weeks of age. After six weeks, significant increases in GSH-Px (P<0.0001) and Cu,Zn-SOD (P<0.0001) activities, with a significant increase in TBARS concentration (P<0.01) were obtained in the heart muscles of the control chickens. At the same time, like in the experimental group, GSH concentrations in the heart muscles of the animals in the control group were significantly decreased (P<0.02). According to the obtained results, during the fattening period, chickens with organic selenium supplementation in the diet maintained their antioxidant systems in the heart muscle more effective, with enhanced GSH-Px, Cu,Zn-SOD and Mn-SOD antioxidant defence. _____________________________________________________________________________________