DIETETICS 



399 



foods are digested by ruminants may be given in per cent, 

 of total amount taken. 



The following table gives the results of some recent 

 observations upon the availability of the proximate principles 

 of oats in the horse and sheep : 



Per cent, digested. 



Eaw protein 



fat . 



fibre . 

 X free extractives 



Horse. 



68-2 



54-0 



7-1 



69-3 



Sheep. 



63-8 

 62-6 

 40-3 

 72-0 



Only about 587 per cent, of the energy of the oats was 

 thus available. 



This shows very clearly that the diet must contain far more 

 energy than is actually required by the animal, that the gross 

 energy of the diet must greatly exceed the nett energy require- 

 ments of the animal. 



With these general considerations we may now take up the 

 feeding of the various kinds of animals. 



2. The energy requirements vary enormously in animals of 

 different species, and even in animals of the same species. 



1. Size must obviously have a marked effect. A big animal 

 requires a greater supply of energy than a small one. But, 

 since in small animals the loss of heat is greater than in large 

 animals, the metabolic processes in these are more active, and 

 more food in proportion to their size is required. 



In this connection it must be remembered that, in con- 

 sidering the influence of size on the energy requirements, we 

 should really consider only the weight of the living tissues, and 

 should neglect the weight of mere practically dead matter, 

 such as fat, skin, hair, hoofs, and the contents of the alimentary 

 canal. This, however, is not easily ascertained. 



