Influence of Temperature, Humidity and Ventilation Rate on the Release of Odour and Ammonia in a Floor Housing System for Laying Hens

The air in floor housing systems for laying hens may be more polluted than in traditional cage systems since gases are emitted from large exposed surfaces of manure and litter. In order to study odour and ammonia concentrations and emissions at different climatic conditions a small scale poultry house (climate chamber) was equipped with a floor housing system were 356 laying hens were kept. Temperature was set to about 12, 15, 20, and 25° C and ventilation rate was set to values between 0.9 and 5.3 m h hen. Temperature, humidity, and ventilation rate were measured as well as odour, ammonia, carbon dioxide and dust concentration. The ammonia concentration was high and exceeded 25 ppm in many of the measurements. Odour emission showed a significant increase with temperature at similar ventilation rate. Both odour and ammonia emissions showed a significant increase with water vapour pressure. In the experiment, odour and ammonia emissions were more strongly correlated to water vapour pressure than to relative air humidity. The results suggest that control of temperature and humidity may decrease concentrations and emissions of odour and ammonia.