136 The Feeding of Animals 



pression of the digestion coefficients is much lessened 

 or does not occur. Many data are cited in support of 

 these generalizations which are worthy of careful con- 

 sideration. 



It is not unreasonable to suppose that the relative 

 quantity in a ration of the several classes of nutrients 

 may have an influence upon the digestive processes, 

 and we should accept the verdict of previous observa- 

 tions in so far as they will bear critical discussion and 

 further investigation. It should be said in the first 

 place, by way of comment, that the carbohydrate ma- 

 terial in the experiments cited has usuall}^ been fed in 

 addition to a basal ration, thus increasing the amount 

 of food consumed, and, as we have seen, this may have 

 an influence upon the proportion of total dry matter 

 digested. In this particular, the experiments have not 

 been logical. 



In the second place, in these experiments, no allow- 

 ance has been made for the metabolic nitrogen in the 

 feces, i. e., that not belonging to the true undigested 

 residue. As this appears to be independent of the 

 amount of protein fed and stands more nearly in rela- 

 tion to the total digested nutrients, it follows that the 

 smaller the proportion of protein in the digested food, 

 the larger the error caused by the waste nitrogen 

 products. A careful study of this point in the light of 

 more recent knowledge might modify the conclusion, 

 reached as to the depression of protein digestion 

 through feeding starch or starchy foods. In all or 

 nearly all the experiments where this effect is appar- 

 ently shown the digestible dry matter of the ration 



