330 PRINCIPLES OF ANIMAL NUTRITION. 
In the case of the extracted straw, for example, there was 
digested in the total of the two experiments : 
Crude fibers nace: cceeewswstaeewss 4033 grams 
Nitrogen-free extract..............4. 888  “ 
Assuming the loss of energy in the methane to have been 0.422 
Cal. per gram of nitrogen-free extract digested (the same as that 
found by Kellner for starch, p. 325), the 888 grams of these sub- 
stances correspond to a loss of 374.7 Cals. Subtracting this from 
the total loss of 2850.2 Cals., we have 2475.5 Cals. as the energy of 
the methane produced from 4033 grams of crude fiber, which is equal 
to 0.614 Cal. per gram. The total energy of the digested crude fiber 
was shown on p. 304 to be approximately 4.220 Cals. per gram. 
Subtracting the loss in the methane, 0.614 Cal., leaves 3.606 Cals. 
as the metabolizable energy of one gram of digested crude fiber. 
A similar computation of the average results upon the other coarse 
fodders affords the figures of the following table for the metabo- 
lizable energy of one gram of digestible crude fiber: 
Digestible Crude Fiber of Loss in Methane, sig er a 
i Cals. 
Extracted straw ......... 22 cece cece eee 0.614 3.606 
Hay fed alone. ii. ncnwamae on nedes wie aw galas 0.909 3.311 
“added to basal ration ............... 0.614 3.606 
Oat straw added to basal ration .......... 0.783 3.437 
Wheat straw added to basal ration......... 1.219 3.001 
The loss of energy in methane, as thus computed, is in all 
instances greater than in the case of starch. Owing, however, to 
the slightly higher value obtained for the gross energy of the 
digested crude fiber, the difference in metabolizable energy between 
starch and crude fiber is somewhat less marked, and is hardly 
sufficient of itself to justify assigning a materially lower nutritive 
value to the latter. 
It is worthy of note also that the loss in the methane appears to 
be a very variable one, justifying the conclusion already reached 
that other factors than the proximate composition of the food ma- 
terially affect the extent of the methane fermentation. 
The Horse-—The production of methane by the horse appears 
to be much less copious than that by ruminants. Lehmann, Hage- 
Digitized by Microsoft® 
