Effect of diet on blood selenium and glutathione peroxidase activity in the alligator

Four groups of immature alligators were fed diets of ground nutria (Myocastor coypus) meat; ground fish (Merluccius spp); nutria plus sodium selenite; and fish plus sodium selenite. Plasma selenium, plasma glutathione peroxidase and erythrocyte glutathione peroxidase (GSH-Px) were measured in blood samples taken 10 days before and at 18, 39 and 60 days after initiating the diets. Selenium concentration and plasma GSH-Px activity remained at low levels in the group fed nutria alone, but increased significantly in the groups fed fish alone, nutria plus selenite and fish plus selenite. Plasma selenium and GSH-Px activity showed a high degree of correlation (r = 0.944). Erythrocyte GSH-Px activity was more variable than the plasma enzyme activity, but increased significantly in the groups fed nutria plus selenite and fish plus selenite by 39 days. In the groups fed fish alone enzyme activity was significantly higher than the group fed nutria alone only at 60 days.