638 NUTRITION OF FARM ANIMALS 



for each 100 grams of total carbohydrates digested, and the 

 estimated results for ruminants recorded in Table 188 for the 

 losses in methane were computed on that basis. With the 

 addition of later unpublished experiments, Kellner's 1 aver- 

 age was increased to 4.3 grams. Later experiments by Armsby 

 and Fries 2 have given slightly higher averages, viz., 4.8 grams 

 for roughages and 4.7 grams for concentrates. No similar re- 

 sults for the smaller ruminants have been reported but probably 

 it may >be safely assumed that the average for cattle is substan- 

 tially applicable to these species also. 



In the horse the principal seat of the methane fermentation 

 is the colon and ccecum (128). Since the more soluble carbo- 

 hydrates of the feed are largely or entirely digested before reach- 

 ing these organs, methane is much less copiously produced 

 than in the case of ruminants and may be regarded as derived 

 chiefly from the fermentation of crude fiber. 



In respiration experiments on mixed rations of oats, hay 

 and straw, Lehmann, Zuntz and Hagemann 3 observed as 

 the result of eight rather discordant experiments an average 

 total excretion of methane of 4.73 grams per 100 grams di- 

 gested crude fiber and in addition an average excretion of 0.203 

 gram of hydrogen per 100 grams digested crude fiber. In 

 more recent experiments, Von der Heide, Steuber and Zuntz, 4 

 using a Regnault-Reiset respiration apparatus (298), obtained 

 for the methane excretion per 100 grams digested crude fiber 

 9.06 grams on hay and 2.28 grams on straw pulp. Using 

 the average of these rather discordant experiments, the fer- 

 mentation losses in the case of the horse may be approximately 

 computed from the amount of crude fiber digested. 



Swine with their simpler alimentary canal suffer but small 

 losses from fermentation in the digestive tract. 



Fingerling, Kohler and Reinhardt 5 found the amounts of 

 combustible gases excreted too small to be determined with 

 their form of Pettenkofer apparatus. Von der Heide and 

 Klein 6 in three experiments with a Regnault-Reiset apparatus 

 obtained the following results : 



1 Ernahrung landw. Nutztiere, 6th Ed., p. 94. 



2 Jour. Agr'l Research, 3 (1915), p. 450. 3 Landw. Jahrb., 23 (1894), 125. 



4 Biochem. Ztschr., 73 (1916), 161. 5 Landw. Vers. Stat, 84 (1914), 197. 



6 Biochem. Ztschr., 55 (1913), 195. 



