Emissions of ammonia, nitrous oxide, and methane from aviaries with organic laying hen husbandry

The first objective of this study was to measure the year round emissions of ammonia (NH(3)), nitrous oxide (N(2)O), and methane (CH(4)) from three commercial aviary systems with organic laying hen husbandry. The second was to determine the effect on NH(3), N(2)O and CH(4) emissions of varying removal interval when using manure belts. Emissions were computed from the ventilation rate, calculated with the carbon dioxide (CO(2)) mass balance method, and gas concentrations of NH(3), N(2)O, and CH(4) inside and outside the hen house. Mean emission per hen for NH(3) was 410 mg d(-1), for N(2)O was 3.12 mg d(-1), and for CH(4) was 81.7 mg d(-1). Mean predicted emission per hen for NH(3) on the first day after manure removal was 298 mg d(-1), and increased by 5.47% d(-1). The presence of manure on the belt did not affect emissions of N(2)O and CH(4). Emission of NH(3) from aviary systems with organic laying hen husbandry was in the same range as emission of NH(3) from aviary systems with non-organic laying hen husbandry. Using organic laying hen husbandry in aviary systems instead of single-tiered systems has the potential to reduce emissions of NH(3), N(2)O, and CH4; further reductions might be realised by changes in litter management. (C) 2011 IAgrE. Published by Elsevier Ltd. All rights reserved.