274 



VETERINARY PHYSIOLOGY 



The rate of waste during a fast depends upon the amount 

 of energy required, and it is therefore increased by muscular 

 work and by exposure to cold (p. 266). 



The power of withstanding starvation depends chiefly 

 upon the extent of the store of fat in the body. Pigs and 

 sheep have been known to withstand starvation for 60 days 



WElGhT 



fAT 



PROTEIN 



Fig, 138. — To show the Effects on the Metabolism of Protein.s and Fats of 

 Feeding a Fasting Animal. The continuous horizontal lines indicate 

 the amount of material metabolised, the broken horizontal lines the 

 amount taken. The differences between tlie levels of these indicate 

 the amount of protein and of fats of the animal body which are 

 metabolised. The first column represents the condition in fasting — 

 the succeeding columns the intake and output each day when food is 

 given. 



and dogs for 80 days without permanent injury. In man 

 fasts of 30 days have been borne without injury. Horses 

 and cattle succumb sooner than men. 



o. 



Metabolism in Semi-Starvation. 



When the food supply of an animal is inadequate to 

 yield the necessary supply of energy, the energy expenditure 

 is reduced by the restriction of all unnecessary movements. 

 Experiments show that, in ruminants at least, the digesti- 

 bility of a ration is increased as its amount is diminished 



