452 PRINCIPLES OF ANIMAL NUTRITION. 
Magnus-Levy’s results, that the work of digestion in man equals 
about 9 per cent. of the metabolizable energy of the food, the 
average results of the experiments are as follows: 
Fasting metabolism... ................00, 2022.4 Cals. 
Metabolizable energy of food............... 4193.4 “ 
Computed maintenance requirement....... 2222.5 * 
Excess £000 sais eaeaeccteeneees eso ¥esea ee 1970.9 “ 
GAIN gk olesg are ares ana ater eS Aina aces ts 1676.0 “ 
Percentage utilization ................0.. 85.0 per cent. 
The computation gives a somewhat lower percentage for the 
utilization of the excess food than that assumed for the availability 
of the maintenance food. 
Experiments on Swine.—Meissl, Strohmer & Lorenz * in their 
investigation upon the sources of animal fat made six respiration 
experiments with swine, the results of which afford some data as to 
the utilization of their food by these animals. In Experiments V 
and VI, made on two different animals, no food was given, and the 
following results were obtained, the energy equivalent to the loss 
of tissue being computed as in Rubner’s experiments in the pre- 
vious chapter: 
Metab- 
Hours , Total olism per 
_ IT x : L L f Li f 
Beper | ee, | Oe | Smmeuay | Maegan | Ganon, | Meee | 10 ee. 
Deg. C. | Feeding. Kgs. Grms. Grms. Cals. Weight + 
als. 
WisSemdins 20 24 140 9.80 224.51 2607 2083 
VI { 20 12 120 9.55 375.78 
ucts 20.4 72 120 6.77 194.93 2291 2029 
The experiment begun only twelve hours after the last. feeding 
obviously gave too high results, owing to the presence of food in 
the digestive canal. That this source of error was substantially 
eliminated after twenty-four hours appears probable from the close 
agreement of the results with those obtained after seventy-two 
hours. The average fasting metabolism per 100 kgs. live weight 
is 2056 Cals. and this average has been made the basis of the com- 
putations which follow, except in Experiment I. This experiment 
* Zeit. f. Biol., 22, 63. 
+ Assumed to be proportional to the two-thirds power of the weight. 
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