Effect of excess dietary copper, iron or zinc on the tocopherol and selenium status of growing pigs.

Two experiments were conducted to evaluate the effect of the addition of high levels of Cu (as CuSO4), Fe (as FeSO4) or Zn (as ZnO) to swine starter and grower diets on performance and vitamin E and Se status. The stability of natural tocopherols in mixed feeds was evaluated during storage. Addition of 1,000 ppm Fe or 1,000 ppm Zn had no effect on rate or efficiency of weight gain in either experiment. In Exp. 1, the addition of 250 ppm Cu improved daily gain and efficiency of feed utilization (P less than .05) during the first 3 wk of the experiment. Copper had no effect on pig performance during the rest of Exp. 1 or in Exp. 2. Serum lactate dehydrogenase or glutathione peroxidase activity was not affected (P greater than .1) by any of the mineral additions. Serum tocopherols were not affected by the mineral treatments in Exp. 1. In Exp. 2, addition of 250 ppm Cu decreased (P less than .01) serum tocopherol levels throughout the 8-wk experiment. The alpha-tocopherol levels of the starter diet decreased (P less than .05) during storage. Addition of 250 ppm Cu (P less than .01) or 1,000 ppm Fe (P less than .05) or 1,000 ppm Zn (P less than .05) increased the destruction of alpha-tocopherol in the starter diet. Alpha- and gamma-tocopherol levels of the starter diet decreased to near zero in 22 d in the presence of 250 ppm Cu. In the grower diet, the addition of 250 ppm Cu (P less than .01) or 1,000 ppm Fe (P less than .05) increased the destruction of tocopherols.(ABSTRACT TRUNCATED AT 250 WORDS)