2r>S 



POULTRY PRODUCTION 



more moisture there is in a building the more opportunity 

 there is for disease-bearing organisms to be present in large 

 numbers. 



^Viti) the moisture of the body being constantly given off 

 by means of respiration and feces the air of the poultry-house 

 is bound to l:iecome laden unless it is as constantly replaced 

 witli new air. 



Fig. 133 



A farm poultry-house haviirg no ventilation. (Courtesy of Piirduc 

 Agricultural Experiment Station.) 



Ventilation. — Ventilation is of profound importance, how- 

 ever, not only because of the relation to the elimination of 

 moisture.' With the moisture of the expired air, gases are 

 also given off, the principal one of which is carbon dioxide. 

 Among these gases are certain ones that are actually poison- 

 ous if rebreathed. They are far more poisonous when 

 breathed by anotlier individual than when breathed by the 

 individual giving them off. There is no reason to suppose 

 that the striking result reported by King,' where a mouse 

 confined in a pint fruit-jar until it was nearly suffocated 

 Hved longer than a perfectly fresh mouse did that was put 

 into the jar at that point, is not holding true in the hen-house 

 continually. Every bird in the flock of fifty or a hundred is 

 compelled to breathe the poisons given oil by all tlie other 



* Phj'sics of Agriculture. 



