FOOD 97 



2. Much less proteid suffices for the body requirements 

 when a proportion of fat exists in the food; this econo- 

 mising influence of fat is better marked in carnivora than 

 herbivora. 



3. Carbo-hydrates exercise a marked preservative action 

 on proteids in herbivora, and effect a true economy. Less 

 proteid is required in the presence of carbo-hydrates, and 

 further, it is better digested. 



Much of the experimental feeding work carried out by 

 Agricultural Stations abroad, has been directed towards 

 ascertaining what proportion the carbo-hydrates should 

 bear to the proteid substance in a diet, under different 

 conditions of nutrition. 



(a) It has been clearly shown that if the amount of 

 supplied proteid is small, while the carbo-hydrates are 

 large, very little fat can be stored up. 



(b) If the carbo-hydrates given be small, and the proteid 

 increased, greater metamorphosis of the proteid tissue 

 occurs, a greater amount of urea is excreted, and only a 

 small quantity of proteid and fat are stored up. 



(c) If the proteid and carbo-hydrate be supplied liberally, 

 and in a deiinite ratio of proteid to carbo-hydrate, both 

 albumen and fat are stored up in the body. 



The ratio of proteid to carbo-hydrate food is known as 

 the nitrogenous or albtiminoid ratio, a consideration of which 

 had better be deferred until the question of fats and carbo- 

 hydrates has been dealt with. 



NON-NITEOGENOTJS SUBSTANCES. 



Fat.— The sources of fat in the body are— 



1. Prom the fat contained in the food. 



2. From that portion of the proteid not converted into 

 urea. There is more carbon and oxygen in proteid than is 

 required to unite with the whole of the nitrogen to form 

 urea, and this excess of carbon and oxygen is stored up 

 as fat One hundred parts of water free proteid can produce 



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