112 PROGRESSIVE POULTRY CULTURE 



parts, the urinary products, the wastes of the system 

 are voided. The digestive system of healthy fowls 

 operates perfectly under natural conditions of food and 

 feeding. 



THE NUTRIENTS. 



The food of fowls consists of digestible and indi- 

 gestible portions. The digestible part furnishes the nu- 

 triment for replenishing the blood. The indigestible 

 part serves to extend the food or gives it a bulk which 

 adapts it to treatment in the digestive processes as it 

 passes through the digestive tract. The nourishing parts 

 of the food are termed nutrients. These are made up 

 of fifteen chemical elements combined into various or- 

 ganic compounds. 



The nutrients may for convenience be divided into 

 several groups. 



1. Mineral Portion: The mineral compounds of 

 the food are frequently termed the "ash constituents" 

 since they remain if the feed-stuff is subjected to com- 

 plete burning. The phosphates of lime are very im- 

 portant mineral substances of the food. Compounds of 

 sodium, potassium, magnesium, iron and chlorine, are 

 also Included and seem to be necessary. Fluorine and 

 silicon are also present. Calcium phosphates play a 

 very important part in the formation of the skeleton of 

 growing fowls and in renewing the bones of mature 

 birdB. 



Calcium also unites with carbonic acid to form the 

 carbonate of lime of which the shells of eggs are mostly 

 made. Chloride of sodium (common salt) seems to be 

 needed in greater quantity than is furnished to the 

 fowls by ordinary feed-stuffs. 



2. Protein Portion: All the parts of the food 

 which contain nitrogen are grouped together as pro- 

 teids. The protein compounds include besides the all- 

 important nitrogen, the constituents of water (wnich 

 are oxygen and hydrogen) and also in some cases sul- 

 phur, phosphorus and iron. The digestible proteids are 

 of great value because these mainly go to make flesh or 



