Date of Award
Doctor of Philosophy
Richard C. Ewan
A series of experiments was designed to study the effect of excess trace minerals on the dietary tocopherols and the subsequent performance of growing pigs. The alpha-tocopheryl acetate level in swine diets was stable during an 84 day storage period in the presence of a standard trace mineral mix (TM), 250 ppm copper (Cu), 1000 ppm zinc (Zn) and 100 ppm manganese (Mn), but was decreased in the presence of 1000 ppm iron (Fe). The level of alpha-tocopherol in diets containing no trace minerals or TM decreased 50% during 84 days storage. The addition of Cu, Fe, Zn or Mn increased the rate of alpha-tocopherol destruction. The addition of Cu decreased alpha-tocopherol levels to near zero after 15 days of storage. The substitution of l% crude soybean oil for corn in the diet increased the rate of alpha-tocopherol destruction in diets containing the TM, Fe, Zn or Mn. The performance and serum enzyme activities of pigs fed diets containing 250 ppm Cu, 1000 ppm Fe or 1000 ppm Zn were not affected by the mineral additions. Serum tocopherol levels were decreased in pigs fed diets containing 250 ppm Cu and 2.9% crude soybean oil. The serum tocopherol levels of pigs fed diets containing 250 ppm Cu without soybean oil were not affected. Pigs fed diets containing 250 ppm Cu that had been stored 14 days prior to use exhibited no vitamin E deficiency symptoms during a 13 week experiment. Dietary selenium levels were.33 to.36 ppm and were considered adequate in all experiments. Tissue alpha-tocopherol levels tended to decrease in pigs fed diets containing Cu. Antibody responses to the injection of sheep red blood cells were not affected by the addition of Cu or by dietary vitamin E level. The results of these experiments suggest that vitamin E/selenium deficiencies reported in the field are not caused solely by the use of excess trace minerals in the diet. However, serum and tissue vitamin E levels can be reduced by feeding 250 ppm copper, suggesting that the pigs do not maintain optimal vitamin E status.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Charles Robert Dove
Dove, Charles Robert, "The effect of excess trace minerals on pig performance and dietary tocopherols " (1988). Retrospective Theses and Dissertations. 9338.