Retention of Dietary Cadmium and the Ameliorative Effect of Zinc, Copper, and Manganese in Japanese Quail

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Abstract
The metabolism of cadmium and the effect of a combined supplement of zinc, copper, and manganese on the retention of low dietary levels of cadmium were investigated in Japanese quail (Coturnix coturnix japonica). From hatching to day 7, birds of both sexes were fed a purified soy protein basal diet (BD) containing (mg/kg) 30 zinc, 5 copper, and 12 manganese. From days 7 to 14, birds were fed 109Cd in either the BD or in a mineral-supplemented basal diet (MSD), which contained concentrations of zinc, copper, and manganese double those present in the BD. Cadmium as cadmium chloride was fed at 0, 62, 125, 250, 500, or 1,000 μg/kg diet. The graded levels of cadmium resulted in a linear, log-dose, log-response accumulation of cadmium in the duodenum, liver, and kidneys. In comparison to the duodenum, the proportion of cadmium retained by the liver and kidney was small. The proportion of 109Cd retained was independent of the amount of cadmium fed. Birds fed the MSD retained less 109Cd in the liver, kidneys, and whole body than birds fed the BD. The cadmium content of the duodenum was not affected by the MSD. The relative accumulation of cadmium from the MSD was 75% and 64% of that of the BD in the liver and kidney, respectively. The section of the digestive tract distal to the duodenum retained less 109Cd when the birds were fed the MSD than when fed the BD. The data suggest that the cadmium concentration in the lower small intestinal tract may be useful for the bioassay of cadmium in human foods. The data demonstrate the beneficial role of moderate excesses of essential elements in decreasing absorption and retention of low dietary levels of cadmium.