COPPER STATUS OF ADULT MALE-RATS IS NOT AFFECTED BY FEEDING AN AIN-93G-BASED DIET CONTAINING HIGH-CONCENTRATIONS OF ZINC

Although previous studies have shown that copper status of rats is com promised when they consume a diet which high zinc, studies using the n ew AIN-93G rodent diet did not show this effect. Because the new diet formulation contains components such as L-cystine and an ultratrace el ement (UTE) mix that might affect copper metabolism, a study was done to determine if these components interfered with the effect of zinc. A 2 x 2 x 2 x 2 factorial study was designed with two dietary concentra tions of copper, 3 and 6 mg/kg of diet; with L-cystine or DL-methionin e; with or without the UTE mb; and with 2 concentrations of zinc, 35 a nd 350 mg/kg of diet. After 5 weeks, assessments of copper status were made. Results showed that serum ceruloplasmin amine oxidase activity, a very sensitive copper status indicator, was not affected by feeding high zinc in the diet. Other status indicators such as serum copper o r liver copper concentrations also were not affected by high-zinc feed ing. It was concluded that the lack of an effect of high zinc on coppe r status when using the AIN-93G diet was not the result of using L-cys tine or UTE in the diet. Dietary UTE stimulated growth in rats fed the marginal-copper diet but not in rats fed the normal-copper diet. Rats fed diets containing DL-methionine had significantly higher concentra tions of liver and intestinal copper than those fed diets with L-cysti ne.