Effects of graded levels of dietary copper on copper and iron concentrations in swine tissues.

In a dose-response study, 120 weanling, crossbred pigs were used to determine the effect of 7.5, 15, 30, 60, 120 and 240 ppm total dietary Cu on animal performance and Cu and Fe stores in selected tissues. Pigs were killed at 56 or 91 kg average body weight. Average daily gain was not affected by dietary treatment. Dietary Cu concentrations of 7.5, 15, 30 and 60 ppm had no appreciable effect on Cu and Fe concentrations in liver and kidney of pigs slaughtered at 91 kg. However, 120 and 240 ppm dietary Cu increased (P less than or equal to .01) liver Cu 4.5- and 16-fold and decreased (P less than or equal to .05) liver Fe by 50 and 60%, respectively, compared with the other dietary treatments. A fit of liver Cu and Fe data to linear plateau models resulted in an inflection point of approximately 60 ppm dietary Cu. Kidney Cu was also increased (P less than or equal to .05) by 120 and 240 ppm dietary Cu, but the magnitude of the change was smaller than that of liver Cu. Muscle Cu and Fe were not significantly affected by dietary Cu.