338 PRODUCTIVE FEEDING OF FARM ANIMALS 



the partially digested feed is passed" on to the gizzard, an extremely 

 powerful grinding organ having a tough and convoluted lining, 

 where it is ground to a very fine state by means of the abrasive 

 action of the stones or grit which the fowl swallows. Pieces of 

 glass have been taken from the gizzard of a chicken that were 

 rounded on the edges and worn as smooth as though ground and 

 polished by hand, and pieces of iron have been removed that had 

 been bent double. Such instances give an idea of the toughness 

 of ihe gizzard lining and the enormous muscular power of this 

 natural grist mill. 



The feed passes from the gizzard into the intestines, where the 

 process of digestion is completed; the digested nutrients are ab- 

 sorbed by the walls and pass into the blood, which distributes them 

 to all parts of the body. The indigestible parts of the feed eaten, 

 together with waste matter which is thrown off by the body and 

 dumped into the lower intestine, are carried on into the cloaca and 

 voided in the form of manure. In poultry the urea and all fecal 

 matter are voided together, the whitish part of the normal drop- 

 pings representing the urea. 



Feed Components. — The body of a fowl is composed of approxi- 

 mately 44 per cent dry matter and 56 per cent water. The dry 

 matter consists of 21.6 per cent protein, 17 per cent fat and 3.8 

 per cent ash. 



Protein is needed to furnish materials with which to build new 

 body tissue, as muscles and feathers, and to replace the old, worn- 

 out body tissue and feathers. The albumen of the egg also consists 

 of proteid material so that the laying hen draws quite heavily on 

 the protein in her feed to meet this need. 



Carbohydrates furnish muscular energy and heat to keep up 

 the body temperature. The carbohydrate nutrients left after meet- 

 ing the needs of the fowl's body for heat and muscular energy are 

 stored in the form of body fat or used to make up the yolk of the 

 egg, which is largely fatty material. 



Fat performs exactly the same function as do the carbohydrates. 

 It is, however, two and one quarter times more concentrated and 

 efficient. 



Ash, including various salts and mineral materials, is essential 

 to a proper functioning of every part of the fowl's body. Among 

 other things it helps build strong bones and rich blood ; strengthens 

 the nails and feather quills, and furnishes the material for the shell 

 of the egg. Without mineral matter the bones would be soft and 

 flexible and unable to support any weight. 



