172 PRINCIPLES OF POULTRY FEEDING 
energy. In vegetable feeding stuffs they constitute a distinct group. 
In animal feeding stuffs they are represented chiefly by the small 
proportion of glycogen present. Their principal elements are 
carbon, hydrogen, and oxygen. Like fat, they contain neither 
nitrogen nor sulphur, but they differ from fat in that they contain 
less carbon and more oxygen. Carbohydrates can usually be pro- 
duced at home; very little should be purchased on a well-managed 
poultry plant, provided there is land enough for the growing of 
the proper crops. As found in feeding stuffs, carbohydrates may 
be divided into two general classes: 
(1) Substances which go to make up the cells or framework of 
the plant, such as cellulose and fibrous materials difficult to sepa- 
rate, represented in the analysis by the term “ crude fibre.” 
(2) Substances illustrated by starches and sugars found stored 
up in cells as reserve material, dissolving readily in water and 
sometimes represented in analysis tables by the term ‘‘ nitrogen- 
free extract.” 
Ash.—The mineral matter in feeding stuffs which supplies the 
incombustible material to the bird’s body is called ash. This 
ingredient is very necessary, especially in the growing of young 
animals, and can be supplied to poultry in the form of grit, shell, 
bone, and feeds such as bran and alfalfa, which are rich in ash. 
Uses of Nutrients in the Body.—All the nutrients in the ration, 
minus the water present, constitute what is commonly termed the 
total dry matter. Each nutrient has a definite work to do in 
nourishing the body. In an efficient method of feeding they must 
all be supplied in abundance and in the right proportion. 
The most obvious use of protein is the production of tissue, as de- 
sired in growing chicks or young animals, the repairing and building 
up of the waste tissue in the adult, and the supplying of material 
which goes into the formation of feathers, claws, and similar parts. 
The second use is exemplified by the part which protein takes in the 
production of the egg. In compounding the ration it must be 
remembered that protein is indispensable and that its place cannot 
be satisfactorily filled by carbohydrates or fat. If, however, the 
protein content of the feed consumed is in excess of that required 
for tissue building and egg production, it is burned in the body 
like carbohydrates and furnishes material for the formation of fat. 
The uses of the carbohydrates and the fats of feeding stuffs are 
so similar that they may be considered together. Three uses are 
given: (1) They are burned and produce heat, which keeps the 
