Effect of irradiated winter milk and cod liver oil on growth of young of milk-fed rats.

Abstract

During an investigation pertaining to the mineral deficiencies of milk, it was observed that the young, born of milk fed rats in February and March, 1926, were smaller, and their rate of growth was far less rapid, than that of any which we had heretofore noted in a long series of milk fed animals. These young were furthermore much smaller than young born of these same mothers during October and September, 1925. The appearance of the young in all groups (6) were so strikingly similar, even though the milk modifications were somewhat unlike, that it seemed as if the difficulty must be inherent in the milk, and not in the added inorganic substances. This was further emphasized by the fact that in two cases in which the mother rats were being used as controls, the animals were receiving only milk with the customary iron and iodine additions.

To determine what constituent of this particular “winter” milk was lacking, we reduced the number of young in each litter to four, and added to the milk rations of the mothers the following substances respectively: Ca₃ (PO₄)₂, Vitamin B preparation, Yeast, and cod liver oil. In no case did we get satisfactory growth. Slight gains were observed with three of the cod liver oil groups. One group receiving the cod liver oil addition died, as did also the group receiving the Ca₃(PO₄)₂.

Besides the small and spindling appearance of these young, it was observed that the skin had a peculiar pink, yellow color, and the fur was very thin and peculiarly wiry. In spots it was quite gone, giving the animals a moth-eaten appearance. A somewhat similar condition in the fur of animals receiving a purified ration, containing cotton seed oil for its chief fat component, seemed to have been corrected by irradiating the food mixture with ultra violet light from a quartz mercury vapor lamp.