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POULTRY BREEDING AND MANAGEMENT 



made where one or the other of these factors is absent. 

 During cold weather there will be less difficulty in securing 

 good ventilation, because there is a more rapid exchange of 

 air where the difference between the inside and outside tem- 

 perature is great. In warm weather when the temperature 

 inside and outside the incubator room is about the same, 

 the air will be stagnant, and the growing embryo will 

 suffer from a lack of oxygen. 



Analysis of air in an underground incubator cellar at the 



INTERIOR OF OREGON STATION INCUBATOR HOUSE 

 On the left tests are being made of carbon dioxide in the incubators. 



Utah Station while incubators were running showed as 

 high as thirty parts carbonic acid gas in 10,000 parts. This 

 is undoubtedly much beyond the limit of safety. At the 

 Oregon Station in an incubator room above ground, analysis 

 showed 9.9 parts, the highest, and an average of 7.5. Tests 

 in May showed more carbon dioxide than in April. 



This is a possible explanation of the fact that chicks 

 hatched in the cool weather have better vitality than those 

 in the warm weather of summer. Incubators are now 

 built with sufficiently sensitive temperature regulation that 



