IRON-METABOLISM IN CHICKS FED VARIOUS LEVELS OF ZINC AND COPPER

Four studies were conducted to determine the effect of high levels of zinc and copper on iron use of the chick. Chicks from the cross of New Hampshire x Single Comb White Leghorn were fed semi-purified diets with adequate (0.58-0.76-mu-mol Zn/g diet) and high (26.0-31.4-mu-mol Zn/g diet) levels of zinc and adequate (0.13-0.17-mu-mol Cu/g diet) and high (3.18-3.50-mu-mol Cu/g diet) levels of copper for 21 days. Fe-59 was fed in studies A-C and injected intraperitoneally in study D. Chicks fed high levels of zinc consistently showed decreased packed cell volumes and depressed concentrations of iron in livers and tibias. The anemia was not attributable to reduced feed and iron intakes. Chicks fed high rather than adequate amounts of zinc excreted 78% rather than 54% of an oral dose of Fe-59. The appearance of Fe-59 in plasma 1 hour after feeding the isotope decreased in chicks fed high rather than adequate levels of zinc. Ingestion of additional copper did not reverse the effects of ingesting high amounts of zinc on iron absorption. Ingestion of the high levels of zinc had minor effects on endogenous iron excretion. The ingestion of additional copper partially counteracted this effect.