The moisture content of shed litter is a primary contributor to odour and dust generation. Litter with a high moisture content generates substantially more odour than dry litter (McGahan and Tucker 2002). Odour emitted from meat chicken sheds is comprised of volatile organic compounds (VOCs) and non-VOCs, which include ammonia, hydrogen sulphide and reduced sulphur compounds (Dunlop 2017). Water held in litter absorbs and retains odorous compounds, which are then transferred into the air in water vapour. This may be a major way odours move from litter to the air (Dunlop 2017).

Odour emission rates are influenced by shed ventilation and the ability to dry litter effectively. Key factors in the drying process are the flow pattern of the ventilation system and the temperature difference between inside and outside sheds.

The degradation of manure and the volatilisation of odorous compounds in litter are strongly impacted by the temperature in sheds. Regulation of temperature is largely achieved through roof insulation, which prevents the accumulation of heat from external radiation. According to McGahan and Tucker (2002), strategies that can assist regulating and controlling the temperature include:

– good roof and wall insulation
– building sheds along an east-west axis to reduce solar radiation
– having large overhangs (e.g. eaves) on buildings
– ensuring adequate ground cover, such as grass, is maintained on areas surrounding sheds to reduce ground radiation.

Excess heat, water vapour and odorous compounds in sheds are removed through ventilation systems. Effective ventilation allows maximum airflow through sheds. This helps remove excess moisture, keep litter friable, promote aerobic conditions and dilute odorous gases that are released into the outside air. Effective shed ventilation regulates the internal shed temperature, which aids in reducing and controlling odour emissions (McGahan & Tucker, 2002).