UTILIZATION OF COPPER IN COPPER PROTEINATE, COPPER LYSINE, AND CUPRICSULFATE USING THE RAT AS AN EXPERIMENTAL-MODEL

One hundred twenty male Sprague-Dawley rats, averaging 108.6 g initial body weight, were used in two feeding experiments to evaluate the uti lization of Cu in Cu proteinate, Cu lysine, and cupric sulfate. In Exp . 1, 60 rats were randomly assigned to 12 treatments in a 2 x 2 x 3 fa ctorial arrangement of treatments, with Zn supplementation at 0 or 100 0 mg/kg diet, Cu supplementation at 5 or 15 mg/kg diet, and Cu form of CuSO4 . 5H(2)O, Cu proteinate, or Cu lysine. The purified basal diet contained .81 mg Cu, 20 mg Zn, and 60 mg Fe/kg diet. Experiment 2 was similar to Exp. 1 except Zn was replaced by Fe. In Exp. 1, feed intake of Cu proteinate (15.74 g/d) and Cu lysine (15.74 g/d) treatments was higher ( P <.05) than that of CuSO4 (15.33 g/d). Body weight gain and feed intake were increased by high dietary Cu at either requirement o r high levels of dietary Zn (P <.05). There were no differences in fee d intake or body weight gain among the treatment groups in Exp. 2 (P > .05). The Cu utilization of Cu proteinate and Cu lysine were higher (P <.05) based on the liver Cu content. The rats fed Cu complexes had a higher liver Fe or Zn content (P <.05) than the rats fed CuSO4, sugges ting that Cu complexes are absorbed via another mechanism that differs from that of inorganic Cu and does not interfere with Zn and Fe. Sple en Cu content may be a sensitive indicator of Cu status. High dietary Zn decreased Cu utilization, but this effect was overcome by high diet ary Cu.