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 the 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 feathers and muscles, 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. 
