94 NUTRITION OF FARM ANIMALS 



fact that the saliva of ruminants contains but little ptyalin, that 

 a considerable digestion of starch is effected. 



In the duodenum, any starch not digested in the stomach, 

 as well as any dextrins, etc., produced by the action of the 

 ptyalin, are subjected to the action of the amylopsin of the 

 pancreatic juice. This enzym, if not identical with ptyalin, is 

 very similar to it but appears to act more energetically. As 

 in the case of ptyalin, the final product of its action is maltose. 1 



The further fate of the maltose resulting from the digestion 

 of starch is more conveniently considered along with that of 

 other disaccharids in a succeeding paragraph. 



132. Fermentation of starch. The organisms producing 

 the methane fermentation in the digestive tract were believed 

 by Tappeiner to attack cellulose specifically and not to act 

 upon other carbohydrates. As regards ruminants, however, 

 this has been shown to *be an error. In G. Klihn's 2 extensive 

 respiration experiments with cattle upon the formation of fats 

 from carbohydrates, considerable amounts of starch were added 

 to basal rations. Invariably this resulted in an increased ex- 

 cretion of methane. Moreover, there was no increase, but on 

 the other hand, more or less decrease in the amount of crude 

 fiber digested, showing that the additional methane must have 

 had its source in the starch consumed. This conclusion is 

 confirmed by the fact that the total excretion of methane was 

 quite closely proportional to the sum of the digested crude 

 fiber and nitrogen-free extract. On the average four parts of 

 methane were produced for each one hundred parts of starch 

 digested. Kellner's subsequent investigations 3 have fully 

 confirmed these results, although giving a lower average, viz., 

 3.07 parts of methane per one hundred parts of digestible 

 starch. Moreover, Kellner's investigations have shown that 

 the methane fermentation is not confined to cellulose and 

 starch but that, as already indicated, the complex of compounds 

 grouped under the head of nitrogen-free extract, including the 

 sugars, is subject to this process. His experiments also show 

 that the proportion of methane produced is somewhat variable, 

 depending upon conditions not yet fully investigated. 



As already stated (128), the chief seat of fermentation in the 



1 See footnote on p. 92. 2 Kellner; Landw. Vers. Stat, 44 (1894), 257. 



3 Landw. Vers. Stat., 53 (1900), 423. 



