THE FOOD AS A SOURCE OF ENERGY. 301 
ENERGY OF DIGESTED ORGANIC MATTER. 
Apparent 
Loss in Metabolizable 
Total Energy. 
Energy, 
baa Urine, | Methane Pi 
e i Per oF 
Gent. | Gens, } Cent. | QR: 
Meadow hay (seven samples)........ 4.439} 9.62] 11.52 | 78.86] 3.501 
Timothy hay ............... 0... eee 4.377| 4.95} 12.33 | 82.72] 3.620 
Oat stiaWi te scdhaaiaeet aoe oe ental 4.514} 4.81] 12.30 | 82.89] 3.740 
Wheat straw. ...........2.2.22205. 4.443} 5.62] 19.89 | 74.49} 3.310 
Extracted straw... 0.0.0.0... 0000e 4.202|—0.91} 14.29 | 86.62) 3.640 
Beet molasses, Sample II........... 4.124) 3.24) 12.52 | 84.24] 3.473 
Starch, Kiihn’s experiments.,....... 4.192)—1.19) 13.42 | 87.77] 3.679 
‘ Kellner’s experiments *.......| 4.012/—0.92} 11.12 | 89.80) 3.603 
Wheat gluten, Kellner’s experiments..| 5.749] 16.59] 0.02 | 83.39) 4.792 
* Average of Samples III and IV. 
in the methane is considerably larger, resulting in a materially 
lower figure for metabolizable energy. 
The results summarized in the two preceding tables, it should 
be remembered, include, as already pointed out, all the effects pro- 
duced by the addition of the material under experiment to the 
basal ration; that is, they give the apparent metabolizable energy. 
In the case of the coarse fodders no other method of computation 
is practicable, and the same would be true in most instances of 
ordinary concentrated commercial feeding-stuffs. In such cases it 
is rarely possible to distinguish with accuracy between the energy 
derived from the material experimented with and the subsidiary 
effects of the latter upon the digestibility of the several in- 
gredients of the ration or upon the losses of energy in urine and 
methane. We may anticipate, therefore, that the results of future 
determinations of the metabolizable energy of ordinary feeding- 
stuffs will of necessity be expressed substantially in the summary 
manner here employed. 
With the nearly pure nutrients used in many of Kellner’s ex- 
periments the case is different. Here it is possible to take account, 
to a large degree, of the secondary effects, such as those, for exam- 
ple, which in the case of wheat gluten result in figures exceeding 
100 per cent. for the apparent metabolizable energy, and to compute 
results which represent more nearly the actual metabolizable energy 
contained in the substances themselves. In these cases, therefore, 
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