EFFECT OF DIETARY SELENIUM ON GLUTATHIONE PEROXIDASE ACTIVITY IN PIGLETS

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Abstract
Two experiments were conducted to measure the effect of dietary selenium on glutathione (GSH) peroxidase activity in plasma and body organs of growing pigs. In experiment 1, 12 piglets weaned at 2 wk and 18 weaned at 4 wk were fed for a period of 5 wk either a selenium-deficient basal diet or the same diet supplemented with 0.1 ppm selenium as sodium selenite. Three levels of dietary vitamin E supplemented as dl-alpha-tocopheryl acetate were also included in this experiment in a factorial arrangement with selenium. Vitamin E was shown to have no effect on GSH-peroxidase activity. In contrast, dietary selenium exerted a significant effect on the activity of the seleno-enzyme in the plasma, pancreas, heart, lungs and kidneys of piglets. The kidneys showed the highest GSH-peroxidase activity of the organs studied. Supplemental selenium resulted in a marked increase in plasma GSH-peroxidase activity of the piglets weaned at 2 wk, and maintained a high level of activity for those weaned at 4 wk. Pancreatic activity of this enzyme in selenium-deficient animals showed a drop to about one-third the activity observed in selenium-supplemented piglets after a 5-wk period. GSH-peroxidase in heart muscle showed the same response that was observed in the pancreas. The reduction in activity of this enzyme in lungs and kidneys was much greater than in pancreas and heart. No measurable amounts of GSH-peroxidase were observed in the liver of piglets either with or without selenium supplementation. In experiment 2, six pairs of male-female piglets weaned at 2 wk of age were fed either a selenium-deficient or a selenium supplemented diet. During the 20-wk period, selenium-supplemented piglets showed an average GSH-peroxidase activity in plasma 8.2-fold higher than selenium-deficient animals. After 2 wk, selenium-deficient piglets showed an extremely low activity of the seleno-enzyme in the plasma. Thus, the measurement of GSH-peroxidase in plasma of the live animal appears to be a reliable index of nutritional selenium status in piglets.