686 NUTRITION OF FARM ANIMALS 



stuff as a whole (i.e., its crude protein) can furnish, irrespective 

 of whether they exist in a soluble, as it were predigested, form or 

 are first produced in the digestive tract of the animal. 



788. Indirect utilization of non-protein by herbivora. In 

 the case of herbivora, especially of ruminants, another factor 

 enters into the consideration of the value of the non-protein, 

 viz., its relation to the ferment organisms which play so large 

 a part in the digestive processes of these animals. 



It was stated in Chapter III (141) that the presence of soluble 

 nitrogenous compounds in the feed tends to stimulate the mul- 

 tiplication and activity of these organisms, thus bringing about 

 an increase in the excretion of methane and in the proportion 

 of carbohydrates apparently digested. It was likewise indicated 

 that the protein produced at the expense of non-protein in the 

 multiplication of the microorganisms might serve as a source of 

 protein to the body and thus bring about an indirect utilization 

 of the non-protein. Much experimental evidence supporting 

 this view is on record, particularly the extensive investigations 

 of Morgen and his associates, which have been discussed else- 

 where 1 by the writer. Three general conclusions regarding 

 the behavior of non-protein in the body were drawn, viz. : 



In ruminants, a conversion of non-protein into protein appears 

 to be effected by the microorganisms of the digestive tract. 

 The extent of this conversion appears to be relatively greater 

 in the case of ammonium salts and asparagin than in that of 

 the non-protein of vegetable extracts. 



The protein thus formed from non-protein seems to be digested 

 subsequently. The apparent formation of indigestible protein 

 observed by some investigators appears to be due to an increase 

 in the metabolic products contained in the feces, caused by the 

 specific action of the vegetable extracts upon the digestive 

 tract. 



By means of its conversion into bacterial protein, the non- 

 protein in the feed of ruminants may serve indirectly for main- 

 tenance and also as a source of protein for milk, and probably 

 for growth, in rations deficient in protein. 



Quantitatively, however, the various forms of non-protein 

 used in these experiments were much inferior to protein and a 

 substitution of the former for the latter caused a marked falling 



1 U. S. Dept. Agr., Bur. Anim. Indus., Bui. 139 (1911). 



