Magnesium Sulfate as a Factor in Retention of Calcium and Phosphorus in Cattle. ∗

Abstract

We 1 reported in connection with a study of a P deficiency in the rations of cattle in parts of Minnesota that the drinking water in the affected regions contains an unusually large amount of magnesium sulfate. This was suspected of being a factor in the mineral deficiency problem because of the well-known antagonism between Mg and Ca, and indirectly because of the close relationship between Ca and P in metabolism. It was shown that aphosphorosis could be produced experimentally in dairy cattle during liberal feeding of prairie hay and oats grown in the affected regions. The diseased condition could be both prevented and allayed by a P supplement in the form of Ca₃(PO₄)₂, bonemeal or NaH₂PO₄; under the latter conditions the feeding of Epsom salt in large (85 gm.) daily doses for an entire year seemed to exert no ill effect. Haag and Palmer, 2 using rats, found that a high Mg diet hindered Ca retention when both Ca and P were low, but that this result was less frequent if either Ca or P were high, and was not apparent when both Ca and P were high. The effects of high Mg on P retention were similar, but not so uniformly depressing when both Ca and P were low, as was the case with Ca retention. High Ca or P, or both, tended to counteract the effects of high Mg. Recently Kramer 3 and co-workers, and also Shipley and Holt 4 have shown that Mg in low concentration can inhibit in vitro calcification of rachitic bones. The former workers found that suitable increments of inorganic phosphates overcome the inhibitory action of Mg.