PRINCIPLES THAT GOVERN FEEDING 167 



Fat is the most abundant by far of the non-nitrogenous 

 organic substances of the animal body. It is found in vari- 

 ous parts of the same, in some places as minute particles 

 and in others as special deposits of considerable quantity. 

 The sources of fat in the body are, first, the fat in the food ; 

 second, the albuminoids or nitrogenous substance in the 

 food, and third, the carbohydrates in the same. Whether 

 the carbohydrates are direct sources of body fat is uncer- 

 tain, but indirectly they certainly are. The presence of ani- 

 mal fat in the animal body has the effect of decreasing the 

 protein consumption and of retarding the tendency to nitro- 

 gen equilibrium. 



Protein consumption means the removal of that por- 

 tion of the nitrogenous substance, that is protein, taken into 

 the body and digested through oxidation and the excretion 

 of worn out nitrogenous tissue. 



Nitrogen equilibrium is that principle which inheres in 

 the animal body through which it eventually puts itself into 

 equilibrium with the nitrogenous constituents which it re- 

 ceives in its food above what is necessary to maintain it in an 

 average condition. This question, significant in its bearing on 

 practical feeding, cannot be elaborated further in this work. 



The following are chief among the influences which fat 

 in the food exerts: (i) It decreases protein consumption 

 and thereby increases protein deposition. Protein deposi- 

 tion means the retention and use of that portion of the ni- 

 trogenous food consumed and digested which remains in 

 the body for a longer or shorter time. It is assimilated as 

 new nitrogenous tissue or as tissue which has replaced old 

 worn out or waste nitrogenous tissue. (2) It decreases the 

 protein consumption in the body and it does so indepen- 

 dently of the protein supply. The protein consumption in- 

 creases and diminishes with the protein supply in the food, 

 and all that the fat does is to diminish it by a certain quan- 

 tity, which will be the same no matter how large the protein 

 supply in the food may be. (3) Like fat in the body it re- 

 tards the tendency to nitrogen equilibrium. Its presence in 



