64 HOW THE ANIMAL USES ITS FEED 



demands of the mature animal at rest, and the bulkier 

 carbohydrates furnish sufi&cient heat. 



Relation of Size to Maintenance. — For animals of the 

 same age, class, type, and kind, the larger the animal, the 

 larger must be the maintenance ration. The protein re- 

 quirements vary directly with the weight of the animal, 

 because the muscular tissue varies directly with the 

 weight. The most of the heat produced in the animal 

 body comes from the carbohydrates and fats in the feed 

 stuff and escapes from the surface of the body. A large 

 animal has proportionally less body surface than a smaller 

 animal of the same class and type. The large animal 

 thus requires somewhat less carbohydrate and fat ma- 

 terial' in proportion to its weight than does the small 

 animal of the same type. 



Other Factors in Maintenance. — The fat animal re- 

 quires a higher maintenance ration than the thin animal 

 because it carries greater weight, and added weight re- 

 quires added energy to move it about. Under ordinary 

 conditions, the higher the external temperature, the 

 smaller the maintenance ration, because there is less 

 radiation of heat from the body surface. Nervous 

 animals are harder to maintain than quiet ones. Animals, 

 also vary in their capacities to digest and assimilate 

 food. Other things being equal, animals of the same 

 general type make about the same comparative uses of 

 the feed given to them, regardless of the breed to which 

 they belong. It is practically impossible to keep a young 

 animal at constant weight during its period of growth. 



Feeding for Meat Production. — Feeding for meat pro- 

 duction accomplishes two ends, growth and fattening. 

 Growth prepares the framework and fattening increases 



