Aug. i6, 191S Phosphorus Metabolism of Lambs 473 



SUMMARY 



(i) There are marked differences in the percentages of the different 

 forms of phosphorus occurring in alfalfa hay, com, and linseed meal, and 

 in the ratio of phosphorus to protein in these feeds. A large part of the 

 phosphorus of alfalfa hay consists of the acid-soluble inorganic form; 

 the phosphorus of corn is equally divided between acid-insoluble and 

 acid-soluble, the soluble being largely organic; and the phosphorus of 

 linseed meal is largely in the acid-insoluble form, the soluble being about 

 equally divided between inorganic and organic phosphorus. 



(2) Upon a ration of alfalfa hay, com, and linseed meal lambs excrete 

 in the urine only two-tenths to five-tenths of i per cent of the total 

 phosphorus ingested. 



(3) The forms of phosphorus excreted in the feces of lambs show that 

 the forms of phosphorus in the feed's consumed undergo marked quali- 

 tative and quantitative changes during the processes of digestion and 

 metabolism. A large proportion of the acid-insoluble phosphorus of 

 the feeds is converted into acid-soluble phosphorus, and a large part of 

 the soluble organic phosphorus is also changed into acid-soluble inor- 

 ganic phosphorus. Therefore, there is relatively only a small percentage 

 of acid-insoluble phosphorus and a relatively large percentage of inor- 

 ganic acid-soluble phosphorus in the feces. 



(4) The results of this metabolism experiment, together with those 

 of the main feeding experiment of 217 days' duration, indicate that the 

 phosphorus requirement for the normal growth and fattening of lambs 

 does not exceed 3 gm. per day per 100 pounds of live weight. 



(5) There is no evidence of correlation between the amounts of phos- 

 phorus retained in the body, on the one hand, and the amounts of phos- 

 phorus ingested, the amounts of protein ingested, or the body weights 

 of lambs, on the other hand. 



(6) Variations in the quantity of digestible protein consumed from 

 1.56 to 3.19 pounds per 1,000 pounds of live weight per day by lambs 

 do not influence significantly the forms of phosphorus in the feces, the 

 total phosphorus in the urine, or the total phosphorus stored in the 

 animal body, expressed in percentage of the total phosphorus ingested. 



