The Partition of Phosphorus in Cow Milk in Relation to Phosphatase and Other Constituents by R. Chanda

It has been shown (Owen, 1948 a, b) that thyroxine increases the percentage of phosphorus in cow milk without affecting the percentages of nitrogen or calcium. Experiments were therefore planned (for preliminary reports see Chanda & Owen, 1949a, b) with the object ofpartitioning the phosphorus in the milk of cows treated with thyroxine to find out whether any particular type of phosphorus compound was responsible for the increase. In the earlier experiments (Owen, 1948a, b) thyroxine decreased the positivity of the balance of nitrogen. It also increased the negativity of the balance of calcium so that more calcium was lost in the faeces than was present in the food and some ofthe calcium in the faeces must have come from skeletal stores. Under these conditions the paradoxical observation was made that thyroxine caused the lactating cow to retainphosphorus more avidly so that metabolism of phosphorus followed neither metabolism of nitrogen nor that of calcium. The results of the present experiments help to explain this. To throw into greater relief any chemical differences between the milk of control cows and of those receiving treatment with thryoxine, a third group of cows was treated with the antithyroid drug, thiouracil.