Fecal Ash Research Articles

Effect of Na EDTA in Diets of Different Iron Levels on Utilization of Calcium, Phosphorus and Iron by Rats

One hundred seventy growing rats were utilized in 2 experiments (Initial weight 150 and 60 gm.) to evaluate the effect of Na2EDTA in diets ranging to 4510 ppm of iron on calcium and phosphorus balance, bone and blood values. The higher levels of iron reduced gain; gain-feed ratio; bone ash, calcium and phosphorus and serum calcium, but increased serum phosphorus and liver iron. In balance studies urinary phosphorus and percent iron retained were reduced while urinary calcium and iron and fecal phosphorus and iron increased as dietary iron increased. Addition of ethylenediaminetetraacetic acid (Na2EDTA) to the diet increased weight gain and bone ash in the diets containing the high iron levels when calcium was fed at 1.02% (Experiment 1) of the diet, but had little effect when dietary calcium was reduced to 0.59% (Experiment 2). The excretion of fecal phosphorus and fecal ash was reduced and the absorption and retention of phosphorus were increased when Na2EDTA was included in the diet. The increasing urinary excretion of iron and the increased iron retention as evidenced in part by higher liver iron levels indicated that the “mucosal block” was only partially effective in limiting iron absorption. This was further substantiated by the increased iron retention at the highest level of dietary iron.