44 



Feeds and Feeding. 



changes made in the supply of protein in the food. Given a 

 supply of protein larger than is necessary to maintain the body 

 tissues, and there will in a few days be an equilibrium between 

 the supply and consumption of protein in the body, the time 

 varying with different animals and with the body condition of 

 each animal. The equilibrium will be reached sooner with a lean 

 animal than with a fat one, and sooner when the animal receives 

 food rich in protein and poor in fat than when the opposite occurs. 



III. Influence of Other Nutrients on Protein Consumption. 



66. Influence of fat. — When fed alone, fat does not decrease 

 protein consumption in the body, as is shown in the following 

 results by Voit with a starving dog:^ 



Feeding fat only, to a starving dog — Voit 



Grams Grams Grams Grams Grams Grams Grams 



Fat per day , 



Protein consumption. 





 170 



100 

 185 



200 

 155 



300 



187 



300 

 165 



340 



205 



350 



291 



Feeding increasing quantities of fat in this case appears to 

 have increased, rather than decreased protein consumption. (82) 



67. Influence of carbohydrates. — When fed alone, carbohydrates 

 have no influence on the consumption of protein and thus act in 

 the same way as fat. The same amount of protein is decomposed 

 in the body when nothing but carbohydrates are fed as when no 

 food whatever is given. 



68. Influence of mixed diet. — When the animal is fed on a 

 mixed diet containing fat, carbohydrates and protein, the con- 

 sumption of protein depends on the supply of protein in the food, 

 as in exclusive protein feeding. The following experiment^ 

 serves as an example: 



1 Zeitechr. f. Biologie, V, p. 329. 

 » Armsby, loc. cit., p. 137. 



Armsby, loc. cit, p. 138. 



