DEFINITIONS AND TECHNICAL CONSIDERATIONS. 345 



m conjunction with other fodders. The influence of grains (nutritive relation 

 1-5 to 8) has not been examined as thoroughly as the importance of the subject 

 demands. The experiments of Hofmeister and Haubuer may be cited : The 

 proportions between hay and oats fed varied from 1-1.76 to 1-3.30; about 78 

 per cent, of the protein of oats was digested. 



Numerous experiments lead one to conclude that when the nutritive relation 

 is 1-5.5 there is no depression in the digestion of a coarse' fodder eaten at the 

 same time as the concentrated by-fodder. When the digestibility is made 

 1-8 to 10. the digestibility of coarse fodder decreases. 



Digestibility of crude protein. The digestibility of crude protein in a fodder 

 depends upon the kind considered, reaching 80 per cent, in some cases. In 

 good hay the digestibility of protein seems to depend upon the proportion be- 

 tween it and the organic substances, while cellulose ^also takes an active part, 

 and has an important influence upon the result. Many formula? have been 

 proposed, having for their object the mathematical determination of the di- 

 gestibility of a fodder. As the results depend upon the percentage of protein, 

 their accuracy rests upon a series of practical experiments giving averages ; 

 the coefficient can then be used to a great advantage. If we admit the 

 theory of a partial fermentation in the intestinal canal as was supposed in dis- 

 cussing the digestibility of cellulose, it must not oe forgotten that there would 

 follow a loss of protein. Tappeimer estimates this to be 10 per cent., which 

 cannot be accounted for; but as regards this assertion, nothing is certain, as 

 the loss may be only apparent, for Kirschner's experiments appear to prove 

 that this loss largely depends upon the percentage of carbohydrates in the 

 fodder. When these are in excess, they prevent the fermentation of protein 

 in the intestinal tube. Before giving some interesting examples of experiments 

 having in view the digestibility of protein and formulae relating to same, it is 

 well to point out their weak side, which is that they are solely based upon 

 chemical transformations and no allowance is made for the physical character- 

 istics, which are variable and must be considered in each special case. The 

 experiments having in view the determination of the digestibility of protein 

 have become so numerous that an average of a few hundred of them gives a 

 coefficient that may be considered mathematically correct. 



Some important observations to determine the influence of pepsin upon the 

 digestibility of protein, were conducted under the auspices of Stutzer. later by 

 Pfeiffer. The fodder was first treated by an acid solution of pepsin, then by an 

 alkaline extract of pancreatic fluid; excrements were also treated in very much 

 the same manner. The results obtained were almost identical with those of 

 the natural digestion of sheep. In five experiments, the fodder used varied 

 in each case. 1st meadow hay, 2d meadow hay and oil cake. 3d same as 

 second but dried diffusion cossettes added. 4th clover hay, 5th clover hay, oil 

 cake and diffusion cossettes fresh. If 100 represents the total protein in each 

 case, the following proportions of crude protein of the ration were not dis- 

 solved or digested : 



