108 Report of Department of Animal Industry of the 



we have a suggestion of the difference induced by the nature of the 

 chemical combination of the phosphorus in the rations. InvExperi- 

 ment II, which is a study of nucleo-protein phosphorus, there was 

 no change in the phosphorus content of the urine but in the other 

 experiment, which was a phytin problem, there is recorded a drop 

 of 99 per ct. when the soluble organic phosphorus compound is 

 withdrawn. Experiment II should be repeated before definite con- 

 clusions are drawn, not only because it is a single experiment, but 

 in that the amount of phosphorus fed in its principal period was too 

 small to maintain even an equilibrium of this element. 



The minimum amount of phosphorus in the urine did not occur 

 in the samples from the end of the protracted low-phosphorus period, 

 as one might have expected; the urine of this period was no poorer 

 in phosphorus than that of Period III. The lowest urinary phos- 

 phorus occurred in the week following the last feeding of calcium 

 phytate. 



From Table IV we see that the animal maintained approximately a 

 phosphorus equilibrium on an intake of twenty-four grams of total 

 phosphorus while giving milk carrying eleven grams of the element, 

 leaving thirteen grams per day for the other physiological functions. 

 The phosphorus requirement aside from the milk production would 

 therefore seem to be about twenty-six milligrams per kilo body 

 weight, as a minimum for this animal. When less phosphorus is 

 given than the organism requires, the physiological functions con- 

 tinue at the expense of the phosphorus previously stored in the 

 tissues of the body. Such a storage takes place when a greater 

 amount of phosphorus than is indicated above is being fed, but this 

 is not in direct proportion to the amounts of the increase as can be 

 readily seen by studying periods I and IV in Table IV. Twenty 

 days of very low phosphorus intake did not materially change the 

 phosphorus balance. This is in harmony with previous experiments. 



Insoluble phosphorus. — The insoluble phosphorus was obtained, as 

 in the previous work, by subtracting the soluble phosphorus from 

 the total phosphorus, and was considered, as in the former experi- 

 ments, to be chiefly nucleo-protein phosphorus. There is less 

 insoluble phosphorus in the washed bran than in the original, because 

 it is carried out mechanically by the water along with considerable 

 starch and gluten. 



An inspection of Table IV shows that when the amount of insolu- 

 ble phosphorus in the ration is changed, the amount of this form of 

 phosphorus in the feces also changes; but when the insoluble phos- 

 phorus in the feed is reduced to 13.5 grams per day, further reduc- 

 tion does not result in corresponding decrease in the amount of this 

 form of phosphorus in the dung. The insoluble phosphorus was 

 very largely changed to inorganic phosphorus. This is not apparent 

 when the amount of intake was less than 13.5 grams, as is indicated 

 by the data in the table for the days following number 13, in which 



