RELATION OF VITAMIN-D TO CALCIUM AND PHOSPHORUS RETENTION IN CATTLE 193

A second trial was run about a week after a supplement of monobasic sodium
phosphate had been added to her ration, to study the effect of added phosphorus
on the calcium and phosphorus retention of vitamin-D deficient animals and to
learn the nature of the mineral retention of such animals receiving a liberal in-
take of both calcium and phosphorus. The animal became worse rapidly and
went off feed so badly that a satisfactory balance trial to indicate the effect of
added phosphorus was not obtained. The results of the trial are shown in Table V.
The fact that a severe breakdown seemed to be hastened would indicate that
the effect undoubtedly was not very favourable.

The phosphorus supplement was now removed from her ration and viosterol
added. As the animal was nearing recovery a third balance trial was run with
the ration, adjusted to duplicate that of the first trial except for the added viosterol.
The results given in Table V show a considerable improvement in both the calcium
and phosphorus retention over that obtained when the animal was mildly deficient
in vitamin-D and thus substantiate the previous observations as to the favourable
effect of vitamin-D.

                                                 DISCUSSION

The favourable effect of vitamin-D on the calcium and phosphorus retention
of calves suffering from a vitamin-D deficiency is strikingly shown by the results
obtained with E-201, E-185, and E-194. The vitamin-D deficiency of these
animals was indicated by sub-normal concentrations of calcium and inorganic
phosphorus in the blood plasma, stiffness, bending of the knees, swelling of the
knee, hock and pastern joints, humping of the back, and often some inanition.
As shown in Table VI, the average daily retention of these calves at an age when
bone mineralization should have been progressing rapidly was only 0.51 grms.
of calcium and 0.24 grms. of phosphorus. When viosterol was added to supply
vitamin-D, and without any other appreciable change in the ration, there was
a marked increase in the calcium and phosphorus retention in every case, the daily
average now being 7.49 grms. of calcium and 2.68 grms. of phosphorus. These
amounts represent essentially normal retentions. The increase brought about
by the vitamin-D administration in from three to seven weeks was approximately
fourteen-fold for calcium and eleven-fold for phosphorus. Coincident with the
marked improvement in the mineral retention there was a prompt return of the
calcium and inorganic phosphorus of the blood plasma to normal concentrations,
and a corresponding improvement in the physical well-being of the calf. With
such decided and consistent results there can be no doubt of the important role
played by vitamin-D in promoting the retention and utilization of calcium and
phosphorus by calves under these conditions.

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