Animal Nutrition. 41 



plying the quantity of nitrogen excreted in the urine by 29.4 

 (^?f=29.4). 



63. The waste of the body.— The food supplies materials for 

 making good the waste which the animal siistains through the 

 living process. When the supply is liberal and exceeds the 

 demands of the system, material may be stored in the body 

 by the formation of flesh or fat, and the animal will gain in 

 weight. If the supply is equal to the material broken down, the 

 live weight of the animal will remain unchanged. When the 

 supply is cut short or entirely withheld, the tissues of the body 

 itself are attacked and the animal loses weight. 



There is a minimum amount of protein absolutely necessary 

 for the maintenance of life. This has been determined by experi- 

 ments in which dogs, cats, rabbits and other animals have been 

 starved, and the daily excretion of nitrogen in the urine deter- 

 mined. During the first days of starvation the excretion of 

 nitrogen, or, what is the same, the decomposition of protein in 

 the body, gradually decreases until after five or six days it 

 remains practically constant. The last portion of the protein in the 

 fluids of the body has then been drawn upon and the body tissues 

 are now being destroyed. After a period of continued starvation 

 the supply from the latter source wUl also be exhausted and the 

 animal dies, the time being determined by the condition of the 

 body at the beginning of starvation. A rise in temperature 

 occurs at the beginning of starvation, followed by a general fall 

 until death takes place. Carnivora or flesh-eating animals can 

 withstand hunger longer than the Herbivora. While dogs and cats 

 have lived until their weights have decreased 33 to 40 per cent., 

 horses and ruminants will die when their weight has been reduced 

 20 to 25 per cent. ^ The age of the animal also influences the time 

 that death occurs from starvation, old animals withstanding the 

 effects of hunger better than young animals. The latter lose 

 weight more rapidly and die after a smaller loss of weight than 

 the former. 2 



1 M. Wilckens in v. d. Goltz, Handb. d. ges. Landwirtachaft, III, p. 88. 

 » Halliburton, Chem. Physiology, p. 834. 



