48 Feeds and Feeding. 



70. Relative effects of fat and carbohydrates. — Experiments by 

 a large number of investigators on tbe influence of fat or carbohy- 

 drates on protein consumption show that the two classes of nutrients 

 are of practically equal value, pound for pound, for this purpose, 

 so that so far as saving protein in the body is concerned they may 

 replace one another. This is an important fact, and shows that 

 the relative fuel value of these two grand divisions of food sub- 

 stances is not a measure of their comparative nutritive effect. 

 (60) 



The importance of the high value of carbohydrates in the 

 formation of flesh is evident. Feeds containing much fat are 

 comparatively costly, are difficult of digestion by Herbivora, and 

 an undue amount of them may prove injurious. On the other 

 hand, the carbohydrates are contained in large proportions in all 

 the common fodders, are low-priced and are readily consumed 

 and digested by Herbivora. The carbohydrates in the food of 

 Herbivora effect what fat does with the Carnivora; they decrease 

 protein consumption and enable the animal to subsist on a much 

 smaller quantity of nitrogenous material than would otherwise be 

 necessaiy. 



71. Influence of amides on protein consumption. — It is now fairly 

 well established that a large majority of the amides found in plants 

 are nutrients proper, that is, when fed they enter the system and 

 are oxidized in the same way as other food nutrients. The 

 experiments of Hermann in feeding a dog with gelatine and 

 tyrosin, a common amide, show that the two feeds can sustain 

 life and even cause a production of flesh, i 



Asparagin, an amide present in most young plants, has repeat- 

 edly been shown^ to cause a gatu of protein in the body when fed 

 with a fodder poor in protein. 



Experiments by Zuntz, « Potthast, * and Weiske and Schulze* 

 are in accordance with the above, and prove that asparagin is a 

 nutrient, and that it saves muscular tissues from decomposition. 



» Vierteljahresschr. der Naturf. Ges. in Zurich XXI, p. 36. 



» Armsby, loc. cit. p. 163. 



» Jahresb. d. Thier Chemie 12, p. 422. 



* Jahresb. d. Thier Chemie 13, p. 344. 



• Zeitechr. f. Biologie 17, 413. 



