NET AVAILABLE ENERGY—MAINTENANCE. 4I9 
materials for productive feeding have been reported and will be 
considered in the following chapter. 
Far.—Rubner’s experiments include one * in which fat was 
fed to a rabbit with the following results: 
| Fasting. Bed eG) arate 
Metabolizable energy of food ............. 0 Cals. 227 Cals. 
SD Oba BAM et desed seen Ste tment deanery Rawal ain dae —101 “ +122 “ 
Gain over fasting metabolism ............)......0..0005 223‘ 
Netsavailability: . sieceacs cee eael gage aen gts [ga nen eapen ies 98.2% 
In connection with his investigations upon cellulose, v. Knie- 
riem ¢ also experimented upon the influence of fat on the metabo- 
lism of the rabbit. The basal ration consisted of milk, to which 
was added in the second period 3.94 grams of dry butter fat per day. 
Computing the amounts of energy by the use of Rubner’s factors 
the results were: 
estore | cancun. | RAre 
Milk and butter fat .......... 207.3 —19.5 
Mille es ec tting oie oe ace eae 169.8 —55.2 
Difference ..............-5 37.5 35.7 95.2 
CaRBOHYDRATES.—Rubner ¢ reports three experiments with 
cane-sugar on a cock from which the following results are com- 
puted: 
Metaboliz- Ca ae 
Food. ship enerey Availability, 
Cals. " Total Over Fast- Per Cent. 
Cals.’ ing Metab- 
% olism, Cals. 
Nothing .........--++ +80 0 —239 
34 grms. cane-sugar......-- 136 —121 118 86.8 
Nothing ........-.0ee eee an a be eo 
45 . cane-Sugar ........ = d 
50 ae a ae priate 200 — 53 205 102.5 
* Zeit. f. Biol., 19, 333. ¢ Ibid., 21, 119. t Ibid., 19, 366. 
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