226 POULTRY BREEDING AND MANAGEMENT 



are cheap or dear in proportion as they contain a high or 

 low percentage of protein. 



Carbohydrates and Fats furnish the fat of the body and 

 of the egg. From them are derived the heat necessary to 

 keep up the temperature of the body. They are burned 

 in the body to furnish the heat and also the energy. It 

 requires energy to digest food; it requires energy to walk 

 and to fly and to scratch, just as it requires steam to drive 



AMOUNT FOR. ONE HEN ron One. 



BALANCED RATION FOR ONE HEN FOR A YEAR 

 Showing the amount and sources of the different chemical constituents. 



the steam engine ; and a considerable amount of food in the 

 form of carbohydrates and fat is used to produce this en- 

 ergy. Most poultry foods contain a larger percentage of 

 carbohydrates and fat for egg production than is necessary, 

 while there is usually a deficiency of protein. To what ex- 

 tent fat in the food influences the egg yield is not definitely 

 known. In experiments by the writer rations containing 

 a liberal amount of fat gave a better yield than others of 

 little fat. The experiments have shown that fowls eat 



