Importance of Magnesium in the Control of Plasma Calcium in the Calf

Abstract

IT has been known for many years¹ that when calves are fed for an abnormally long time on milk only they usually, sooner or later, become hypomagnesæmic. In my experiments, four out of sixteen calves fed to about five months of age or more on milk without supplementary vitamin D showed neither hypomagnesæmia nor hypocalcæmia while the remainder became hypomagnesæmic. Of the latter, all but one showed a fall in plasma calcium more or less closely correlated with the fall in plasma magnesium. An example is shown in Fig. 1 and other examples have been reported previously². My work has shown fairly clearly that the hypomagnesæmia is due to magnesium deficiency resulting from a decrease in the ability of the calves to absorb dietary magnesium as they get older³, but the reason for the hypocalcæmia is less clear.