Ammonia Extraction by Ventilation of Loose-housing Systems for Laying Hens

Laying hens kept in loose-housing systems instead of in cages generally mean that more manure is stored in the buildings. This causes an increased release and concentration of ammonia derived from manure and straw bedding material. Removing as much as possible of the exhaust ventilation air adjacent to surfaces with exposed manure reduces the concentration of ammonia. In such a situation, it is important to achieve uniform extraction along the entire length of the building. Both theoretical analyses and model experiments have shown that there are good opportunities to create uniform ventilation along exhaust air ducts if the ratio between the area of the vents and the cross-section of the air channel is of the same size range. Investigations conducted in a loose-housing system for laying hens have shown that ammonia concentrations may be reduced by extracting the air in the proximity of the litter without the risk of increased emissions elsewhere in the buildings.