Iron mobilization and plasma ferroxidase factors in chickens

Hematological values, metal content (Fe, Cu, Zn, Cd) in plasma and liver, ceruloplasmin (p-phenylendiamine oxidase) and ferroxidase activity in plasma, were analyzed in chicks, fed during 10 weeks on a commercial diet, supplemented by either 5,000 ppm Zn or 100 ppm Cd. A microcytic and hypochromic anemia was evident in both groups but in the Cd-fed chicks, plasma iron and ceruloplasmin values were normal. Estrogen administration mobilized iron in the Cd-group but not in the Zn-group. The precipitation of plasma phosvitin reduced (90%) the ferroxidase activity that had been previously induced by the estrogens. Correcting copper levels in the Zn-group, by copper injection, restored the ceruloplasmin level. However, the estrogens, in such birds, neither mobilized the plasma iron nor increased the ferroxidase activity. Plasma citrate was determined in laying, non-laying hens and in estrogenized or normal males. The contribution of citrate to the ferroxidase activity of plasma during the laying period, was negligible. It was concluded that plasma phosvitin during laying was the main factor responsible for the ferroxidase activity. However, the ceruloplasmin in chickens, could play a secondary role in iron mobilization.