DIGESTIBILITY OF SOME ANIMAL FATS. 17 



Data of digestion experiments with butter in a simple mixed diet — Continued. 





Weight. 



"Water. 



Protein. 



Fat. 



Carbo- 

 hydrates. 



Ash. 



Experiment No. 120, subject E. M : 



Grams. 

 2, 198. 



294.0 

 1, 194. 



105.0 



Grams. 



1,024.0 



25.0 



1,037.6 



Grams. 



37.2 



39.4 



9.5 



Grams. 



348.8 



3.2 



2.4 



Grams. 

 762.5 

 221.7 

 138.5 

 105.0 



Grams. 

 25.5 



4.7 



Fruit 



6.0 



















3,791.0 

 84.2 



2,086.6 



86.1 

 24.1 

 62.0 



354.4 



15.2 



339.2 



1. 227. 7 



34.8 



1,192.9 



36.2 





10.2 







26.0 

















72.0 



95.7 



97.2 



71.9 











Average food consumed per subject per day. 



1,072.7 



578.7 



29.8 



99.5 



354.4 



10.5 



Summary of digestion experiments with butter in a simple mixed diet. 



Experi- 

 ment No. 



Subject. 



Protein. 



Fat. 



Carbo- 

 hydrates. 



Ash. 



85 



R. L. S 



Per cent. 

 78.3 

 63.3 

 70.0 

 66.3 

 66.9 

 74.2 

 73.3 

 72.0 



Per cent. 

 93.0 

 95.3 

 91.2 

 96.3 

 90.9 

 94.7 

 93.7 

 95.7 



Per cent. 

 97.7 

 95.6 

 95.3 

 96.4 

 96.5 

 96.3 

 96.2 

 97.2 



Per cent. 

 76.0 



86 



I. D. B 



67 2 



87 



W. D 



58 5 



88 



E.M 



71.9 



117 

 118 



I.D.B 



51.3 

 70.9 



119 



W. D 



52.1 



120 



E. M 



71.9 











70.5 



93.9 



96.4 



65.0 









Having an average digestibility of 93.9 per cent, butter fat may be 

 considered more completely assimilated than any of the other animal 

 fats considered in this report. Though a reasonable allowance of 

 butter is 3 ounces, or 85 grams, per man per day, the experiments as 

 a whole emphasize a fact of common experience, namely, that some- 

 what larger quantities of butter (100 grams per day at least) may be 

 eaten in ordinary circumstances and utilized without any noticeable 

 physiological disturbance. 



ALLOWANCE FOR METABOLIC FAT. 



The coefficients of digestibility given in the preceding discussion 

 are gross rather than net values. They have been derived in the 

 customary way by analyzing the food eaten and the feces excreted 

 during an experimental period to determine especially what proportion 

 of the ingested fat was available for the maintenance of the needs of 

 the body. For this purpose the total ether extract of the feces has 

 been taken to represent the actual quantity of undigested fat — the 

 unavailable residuul of the f;il eaten during the experimental period. 

 That this assumption is not strictly true is apparent from a study of 

 the composition of the feces. It is well known that the feces contain 

 not only undigested residues of food, but certain other waste materials, 



