HOUSING OF POULTRY 175 



heat, in our present state of knowledge, is also unreason- 

 able. 



Ventilation. A good poultry house should be well ven- 

 tilated. Fowls require considerably more fresh air than 

 farm animals. It has been estimated that a hen, in pro- 

 portion to her weight, requires double the weight of oxygen 

 that a man or a horse requires. The amount of air 

 breathed per thousand pounds live weight of hens is given 

 by King as 8,272 cubic feet in 24 hours ; the requirements 

 of a man being 2,833 and a cow 2,804 cubic feet. 



Experiments at the Wye (England) Agricultural Col- 

 lege showed that the health of the fowls bears a close re- 

 lation to the amount of carbonic acid gas in the house. 

 It was found that air in houses with proper ventilation 

 should not contain to exceed nine volumes of carbonic acid 

 gas to ten thousand volumes of air. The ordinary air in 

 country districts contains about three parts. It would be 

 impossible to arrange ventilation so that the air in the 

 poultry house would be as pure as that of outdoors, but 

 from the experiments quoted it is safe to assume that 

 nine parts or under is not injurious. 



When we speak of air being impure we think of the 

 carbonic acid gas in it, yet this gas in itself is not poison- 

 ous. It is harmless, but associated with it is some other 

 impurity, the exact nature of which is not known, that is 

 poisonous. The presence, however, of carbonic acid gas 

 is a sure indication that the air is impure. 



Ventilation, therefore, resolves itself into a question of 

 maintaining a low carbonic acid gas content in the poultry 

 house. The more and larger the openings in the house, 

 the more rapid the exchange of air and the lower the 

 carbonic acid gas content. Reducing the number of fowls 

 in the house decreases likewise the carbonic acid gas. 

 Again, weather conditions will influence the amount. In 



