thf: fekding of ihk animal JU 



of its digestive processes, tears down these sub- 

 stances, setting free tlie energy and transforming 

 the matter into forms suitable to bf inror{>oratrd 

 into animal tissu*'. 



430. Before the matter of the fochh-r can be 

 used, it is necessary that tiie animal expend energy 

 upon it <luring the processes of digestion an<l as- 

 simihition. The profit of tlie fodder to the animal 

 i«; representee! by the dilTerenee Ix'tween tlie 

 amount of energy originally present in the fodder 

 and the amount of energy it is necessary for the 

 animal to expen<l upon it in order to make it 

 availaide. Some substances re<]uire so great an 

 expenditure of energy by the animal to digest or 

 partially digest them that they are useless as 

 fo.lder^, although they uiay contain the proper 

 compound-; in nieasiu'ably jiroper proportions. 



4.11. Fodder is used by the animal (1) as fuel 

 to keep up the bodily heat, without which the 

 vital processes cannot go on; (2) to rejiair the 

 wastes of the various tissues, organs an«l fluids of 

 the body; (3) to form new tissues or organs, or 

 add to those already formed (especially in young 

 animals); (4) to produce young; and (5) to lay 

 up reserve stores in the form of fat or otherwise, 

 to secrete various products, or to perform nmscu- 

 lar lal>or Many of these re.serves or products 

 are useful to man, as milk, wool and t'ixix^. 



432. In general, if the amount of food is 



