NET AVAILABLE ENERGY—MAINTENANCE. 419 
« 
materials for productive feeding have been reported and will be 
considered in the following chapter. 
Fat.—Rubner’s experiments include one * in which fat was 
fed to a rabbit with the following results: 
| Fasting. Hed 7 ea, 
Metabolizable energy of food ............. 0 Cals. 227 Cals. 
Total gain: oe... ios Seen a ae ie ewes —10l1 “ +122 “ 
Gain over fasting metabolism ............)...-.--00 00 ee 223 “ 
Net availability’ co's es ndicuatew siamese soe ee wenss gee fe 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: 
wecbane | cxnvcan. | Myretan, 
Milk and butter fat .......... 207.3 —19.5 
Millen ct eekats ad winch aude whe 169.8 —55.2 
Difference ......-......++- 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- Gain. Nee 
Food. ae eae Availability, 
Cals. ” Total, Over East Per Cent. 
Cals. | Glism, Cals. 
Nothing .........00-eee ee: 0 —239 
34 ae. cane-sugar......-- 136 —121 118 86.8 
Nothing ........--+++-+++: en = ie — 
grms. cane-sugar ........ — : 
4 © we o anew ee 200 — 53 205 102.5 
# Zeit. f. Biol. 19,333.  t Zbid., 21,119. —t Ibid., 19, 366. 
