Ammonia, greenhouse gas, and particulate matter concentrations and emissions of aviary layer houses in the Midwestern USA

There has been an increased interest in alternative housing for laying hens in certain parts of the world, including the United States. Associated with the movement are many questions to be addressed concerning sustainability of such systems. This study continually quantifies concentrations and emissions of ammonia (NH₃), carbon dioxide (CO₂), methane (CH ₄), and particulate matters (PM₁₀and PM_2.5) for two side-by-side aviary barns each housing 50,000 Hy-Line brown laying hens, located in the Midwestern US. The gaseous concentrations were continually monitored using a photoacoustic multi-gas analyzer, while the PM concentrations were measured with tapered element oscillating microbalances (TEOMs). Barn ventilation rate was determined through monitoring the operation time of ventilation fans that had been calibrated in-situ. Nineteen consecutive months of monitored data (June 2010 - Dec 2011) are analyzed and presented. Daily indoor NH₃, CO₂, CH₄, PM₁₀, and PM_2.5 concentrations (mean ±SD) were 8.7 (±8.4) ppm, 1,636 (±1,022) ppm, 10.0 (±6.8) ppm, 2.3 (±1.6) mg/m ³, and 0.25 (±0.26) mg/m³, respectively. The aerial emissions are expressed as quantities per hen, per animal unit (AU, 500 kg body weight), and per kg of egg output. Daily emission rates were 0.15 (±0.08) NH₃, 75 (±15) CO₂, 0.09 (±0.08) CH₄, 0.11 (±0.04) PM₁₀, and 0.008 (±0.006) PM_2.5g/bird. The results are compared to reported emission values for conventional (high-rise and manure-belt) US laying-hen housing systems. Data from this study provide baseline concentration and emission values from the aviary housing system in the Midwestern US.