Composition of rats on low magnesium diet.

Abstract

Three rats were fed on diets of purified casein, glucose (cerelose) and cod liver oil, with a salt mixture of NaCl, CaCO₃, K₂HPO₄ and Fe₂(SO₄)₃. Analysis of the ash of samples of these diets showed that they contained 1.2 mg. magnesium per 100 gm. of diet. The rats were kept on the diets 20, 20 and 100 days respectively. The ash of the rats contained 23, 14 and 31 mg. magnesium, or 0.030, 0.029 and 0.026 per cent of their respective body weights. The corresponding control rats contained 24, 15 and 36 mg., which was .039, .043 and .037 per cent of their respective body weights. Estimating that rat No. 3, which weighed 52 gm. at the beginning of the experiment, contained about .040 per cent magnesium, or 21 mg. magnesium, it gained approximately 10 mg. During the same period, it ate about 1000 gm. diet, containing 12 mg. It must, therefore, have absorbed and retained nearly all the magnesium it received. This is in marked contrast to its inability to utilize all of the Ca and P of a diet, even when they are present in inadequate amounts.