278 PRODUCTIVE FEEDING OF FARM ANIMALS 



in the muscles goes on faster than the repair of muscles from the 

 feed supplied, the horse will lose weight. This frequently happens 

 when a horse is working hard for a considerable period of time and 

 does not receive a sufficient quantity of easily digestible feed (con- 

 centrates). 



Character of Feed Required. As the muscles are largely com- 

 posed of proteins, it might be supposed that the decomposition of 

 protein in the body would increase with the amount of labor per- 

 formed; such is not the case, however. The oxidation of non- 

 nitrogenous materials in the body, on the other hand, Increases 

 rapidly when hard work is done. A part of the energy thus set 

 free appears as heat, and another part as mechanical work. The 

 oxygen required for the oxidation processes going on in the body is 



FIG. 68. Draft horses that give a good account of themselves in the show ring, as breeding 

 animals and for doing heavy work. (Pacific Rural Press.) 



supplied by the blood, and the oxidation products formed, carbon- 

 dioxide and water, are exhaled through the lungs and in the per- 

 spiration. The result of heavy work is, therefore, seen in an in- 

 creased consumption of oxygen and an increasing excretion of 

 carbon-dioxide and water. This is also what takes place when 

 mature fattening animals are gaining weight. The carbohydrates 

 or fat, or both, are the main sources of energy supply both in the 

 production of body fat and muscular energy, and it is not neces- 

 sary to furnish more protein to working animals than in the case 

 of fattening animals, viz., sufficient to insure a complete digestion 

 of the feed. For this purpose a nutritive ratio of 1:8 or 1 : 10 

 will suffice. 



A growing animal that is performing work requires a special 

 supply of protein, and the same appears to be the case with race 

 horses or driving horses which perform heavy work within a short 



