422 THE ESSENTIALS OF AGRICULTURE 



harmful gases. Hens require more air per unit of weight than 

 other farm animals. It has been estimated that a looo-pound 

 cow breathes 2804 cubic feet of air in twenty-four hours, that 

 a looo-pound horse breathes 3401 cubic feet in the same time, 

 while 1000 pounds of hens require 8278 cubic feet. 1 In the 

 henhouse where there are a good many birds, if the poisonous 

 gases produced by the fowls are not carried off, they will be 



FIG. 215. White Plymouth Rocks 



breathed repeatedly, to the great injury of the fowls. Sunshine 

 is essential because it helps keep the house dry, makes it more 

 cheerful, and is a great germ destroyer. 



Although chickens are many more generations removed 

 from their wild ancestors than are turkeys, nevertheless both 

 are still very sensitive to crowding. Under conditions of domes- 

 tication the flocks are large and are likely to be crowded into 

 a rather small house. To promote egg production and insure 

 health it is wise to provide 4^ or 5 square feet of floor space 

 for each chicken. 



561. Sanitation in chicken houses. Surface parasites and 

 disease are dangers that constantly beset chickens. The success- 

 ful poultry keeper must continually guard against these things. 



1 King, Physics of Agriculture, p. 355. 



