Effects of starvation and refeeding on tissue zinc, copper and iron in turkey poults

Abstract

The effects of starvation and refeeding of 2-wk-old turkey poults on serum and tissue levels of zinc, copper and iron were investigated. Serum concentrations of zinc and copper declined during 4 d of starvation. Refeeding for 24 h following a period of starvation restored serum copper to levels similar to those in the fed controls but failed to elevate zinc levels. Liver concentrations and total quantities of zinc, copper and iron increased throughout starvation. Refeeding the starved poults reduced hepatic metal concentrations but caused a further increase in total metal content. This was apparently related to the large increase in liver mass, and the effect was most pronounced in poults starved 1 d prior to refeeding. Starvation also caused an increased zinc concentration and content and a reduced copper content in the pancreas, duodenal mucosa and kidney. Iron content of the pancreas and kidney increased during starvation, but that of the duodenal mucosa declined. Starvation evoked a progressive increase in the cytosolic zinc concentration from liver, pancreas, duodenal mucosa and kidney. A major part of this increase was accounted for as zinc bound to metallothionein (MT). Refeeding rapidly reduced cytosolic and MT-bound zinc in each of these tissues. It was concluded that starvation and refeeding had major effects on tissue trace metal status. A function is proposed for MT during starvation as a mechanism for the conservation of body zinc stores. Zinc, released as a consequence of tissue catabolism, is repartitioned into a soluble storage site (MT), which can be rapidly mobilized to meet the demands of new tissue synthesis once anabolic metabolism resumes.