A STUDY OF THE METABOLISM AND PHYSIO- 

 LOGICAL EFFECTS OF CERTAIN PHOSPHORUS 

 COMPOUNDS WITH MILCH COWS, IL * 



A. R. ROSE. 



SUMMARY. 



The chief aim of this experiment was to check the results reported 

 in Technical Bulletin No. i, of this Station, by repeating the work 

 in such a way as to eliminate more of the variable factors. This 

 was effected by adjusting one of the animals used in the previous 

 experiments to a lov/-phosphorus ration very nearly identical with 

 the one formerly employed and adding thereto the calcium salt 

 of phytin. 



In this, as in the former experiments, the organic phosphorus in- 

 gested was eliminated very largely in the form of inorganic phosphorus 

 by way of the intestine, the amounts of phosphorus in the urine being 

 very small. When phytin was withdrawn from the ration, the 

 decrease of phosphorus in the urine was immediate; when phytin 

 was added, a rise in phosphorus occurred after a lag of two days. 

 Phytin caused more phosphorus to be eliminated through the kidney 

 than did whole wheat bran. The long duration of the low- 

 phosphorus period did not in itself affect the phosphorus content 

 of the urine nor the phosphorus balance. 



The insoluble phosphorus of the feces diminished with decreasing 

 amounts of insoluble phosphorus in the rations, when the latter 

 ranged above fourteen grams. 



The soluble organic phosphorus disappeared very largely from 

 the alimentary tract. The apparent utiUzation was poorer in the 

 low-phosphorus periods and in the calcium phytate period than in 

 the whole-bran period. 



For maintenance of phosphorus equiUbrium in this species of 

 animal the requirement would seem to be the amount of phosphorus 

 eliminated in the milk plus twenty-six milUgrams per kilo of body 

 weight; an excess over this amount causes phosphorus retention, 

 and smaller quantities result in loss of phosphorus from the 

 organism. 



The addition of calcium phytate increased the potassium both in 

 the urine and dung, and changed the path of elimination of part of 

 the magnesium from the kidney to the intestine. The calcium 

 added as calcium phytate was almost entirely eliminated by the 

 intestine immediately after administration. The calcium of the 

 urine increased with decreasing phosphorus in the rations and 

 decreased when calcium phytate was added. 



*A reprint of Technical Bulletin No. 20, May, 1912. 



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