THE FEEDING OP THE ANIMAL 247 



without change. For this reason it is often con- 

 venient to consider it in a class by itself. So far 

 as it is used at all, it serves the same purpose as 

 the other carbohydrates. 



3/. Fats 



448. The fats (371a) of fodder are used by 

 the animal for much the same purposes as the 

 carbohydrates. They contain only carbon, oxy- 

 gen and hydrogen, but proportionately much 

 less oxygen than the carbohydrates. For this 

 reason they yield much more energy when de- 

 composed or burned, and are, therefore, of 

 much more value to the animal than the carbo- 

 hydrates. 



449. The amount of energy yielded by differ- 

 ent fats varies somewhat, but in general, it is 

 about two and one -fourth times as much as that 

 yielded by an equal weight of sugar or starch ; 

 and in reducing fat to its "starch equivalent" (for 

 purposes of comparison) this is the factor com- 

 monly employed. In ordinary fodders the per- 

 centage of fat is not large, running from about 

 3 to about 8 per cent of the air- dry substance. 



4. Feeding 

 4a. Nutritive ratio 



450. From what has already been said, it will 

 be seen that the protein, carbohydrates and fats 



