180 CHEMISTRY OF FARM PRACTICE 



ing animals make economical use of large amounts of pro- 

 tein. It is not desirable to feed large amounts of protein 

 to mature animals unless they are either pregnant, or giving 

 milk, or producing wool, because the protein eaten above the 

 amount needed for maintaining the body tissues is un- 

 economically used. 



The protein of the milk which the young animal takes is 

 very largely stored in the body. Soxhlet found that 72.6 

 per cent of the protein, 96.6 per cent of the lime, and 72.6 

 per cent of the phosphorus fed in the milk was stored in the 

 body of a calf between two and three weeks old. The 

 proportion stored diminishes as the animal approaches 

 maturity. 



Growing animals should get an abundance of succulent, 

 highly nitrogenous forage plants. These plants usually 

 contain a liberal amount of mineral elements. Some con- 

 centrate (such as bran, meal, oats) is usually desirable and 

 an abundant supply of common salt. 



123. Maintenance Rations. A certain amount of food 

 is required by mature animals to perform the body functions, 

 such as furnishing heat to maintain the body temperature, 

 energy to perform the vital functions, and various materials 

 to replace the waste tissue that is constantly being broken 

 down. This is known as the maintenance ration. If it is 

 too much reduced, starvation will result. 



These rations may consist largely of coarse hay and straw 

 or " roughages," as they are called. The main requirement 

 is the production of heat, and roughages contain a large 

 amount of carbonaceous material, which produces heat eco- 

 nomically. Very little protein is required in the maintenance 

 ration, because protein is only needed for the replacement of 

 waste tissue, a requirement which is low in mature animals. 



Experiments have shown that the temperament of the 

 animal, the condition with respect to flesh, the conditions 

 under which the animal is kept, the body covering and the 

 bodily surface exposed, and the severity of the weather all 



