Agriculture accounts for 10 to 12% of the World's total greenhouse gas (GHG) emissions. Manure management alone is responsible for 13% of GHG emissions from the agricultural sector. During the last decade, Québec's egg production systems have shifted from deep-pit housing systems to manure belt housing systems. The objective of this study was to measure and compare carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) emissions from three different cage layer housing systems: a deep liquid manure pit and a manure belt with natural or forced air drying. Deep liquid manure pit housing systems consist of "A" frame layer cages located over a closed pit containing the hens' droppings to which water is added to facilitate removal by pumping. Manure belt techniques imply that manure drops on a belt beneath each row of battery cages where it is either dried naturally or by forced air until it is removed. The experiment was replicated with 360 hens reared into twelve independent bench-scale rooms during eight weeks (19-27 weeks of age). The natural and forced air manure belt systems reduced CO₂ (28.2 and 28.7 kg yr(-1) hen(-1), respectively), CH₄ (25.3 and 27.7 g yr(-1) hen(-1), respectively) and N₂O (2.60 and 2.48 g yr(-1) hen(-1), respectively) emissions by about 21, 16 and 9% in comparison with the deep-pit technique (36.0 kg CO₂ yr(-1) hen(-1), 31.6 g CH₄ yr(-1) hen(-1) and 2.78 g N₂O yr(-1) hen(-1)). The shift to manure belt systems needs to be encouraged since this housing system significantly decreases the production of GHG.
Keywords: belt; deep-pit; emission; greenhouse gas; housing; laying hen.