Impact of copper deficiency in cattle on proteins involved in iron metabolism

Abstract

A study was conducted examining the impact of long‐term Cu deficiency, either alone or in the presence of high Mn, on Fe metabolism in cattle. Twenty‐one Angus calves were born to cows that had been fed one of the following diets: 1) Cu adequate (10 mg supplemental Cu/kg; +Cu), 2) Cu deficient (no supplemental Cu and 2 mg supplemental Mo/kg; –Cu), and 3) Cu deficient diet plus 500 mg supplemental Mn/kg (−Cu+Mn). After weaning calves remained on the same treatment as their dam and remained on study for 275 days until harvest. Duodenal scrapings for protein isolation were collected at harvest. Plasma Cu and Fe concentrations were lower (P < 0.05) in –Cu vs. +Cu and were further decreased (P < 0.05) in –Cu+Mn vs. –Cu. Liver Cu was greater (P < 0.01) in +Cu vs. –Cu. Based on Western blotting, Cu chaperone protein (CCS) was increased (P < 0.05) in –Cu vs. +Cu but did not differ between –Cu and –Cu+Mn. Levels of hephaestin, a Cu‐dependent ferroxidase, were greater (P < 0.05) in –Cu+Mn vs. –Cu, and the iron export protein ferroportin also tended (P = 0.06) to be greater in –Cu+Mn vs. –Cu. Hephaestin and ferroportin levels were not different between +Cu and –Cu. Although liver Fe was elevated in –Cu+Mn calves compared to +Cu calves, concentrations of hephaestin and ferroportin were increased in –Cu+Mn calves, suggesting that proteins involved in Fe absorption were regulated in response to low circulating Fe rather than in response to elevated storage Fe.