io8 SCIENTIFIC FEEDING OF ANIMALS 



undergoing decomposition to the same extent as 

 when the animal is completely at rest. 



If the materials in the food do not yield enough 

 energy for the work which the animal is performing, 

 the body fat is drawn upon, and when this reaches 

 a certain minimum the protein has to supply the 

 rest of the energy required. 



All those organic substances capable of yielding 

 dynamic energy (p. 57), whether coming from the 

 food or from the body fat or protein, are the source 

 of muscular energy. 



(c) Storage of protein in consequence of muscular work. 



The food does not alone determine the quantity 

 of work that an animal can perform. The muscular 

 system, which is the apparatus for the performance 

 of work, must also be properly grown. A man 

 whose muscles are feebly developed cannot perform 

 as much work as a robust man would do on the 

 same diet. If, however, a man, still capable of 

 development, is obliged to use his muscles regularly, 

 they become stronger and increase in size with the 

 daily exercise. In consequence of such conditions 

 the performance of work can lead to an increase of 

 flesh, as has been satisfactorily proved in numerous 

 experiments. 



Experience has taught that for the proper develop- 

 ment of young cattle sufficient exercise, that is the 

 use of the muscles, is necessary. 



