Ammonia and greenhouse gas emissions from an enriched cage laying hen facility
Ammonia, methane, nitrous oxide and carbon dioxide emissions were measured during a complete production cycle in an enriched cage laying hen facility under Oceanic climate conditions. Continuous monitoring of gas concentration, ventilation rate and environmental parameters were conducted from April 2012 to September 2013. The seasonal and diurnal pattern of gas emissions was analysed. Seasonality effect was found for NH 3 emission, showing an average emission of 144.9 mg d 1 hen 1 and 90.3 mg d 1 hen 1 in summer and winter, respectively. On the contrary, diurnal pattern of NH 3 emission did not differ between these seasons. For CO 2 mean emission values did not show seasonality, although the diurnal pattern differed between winter and summer. Results obtained for CH 4 and N 2 O emissions did not provide sufficient evidence to determine either seasonality or diurnal effect on these gases. An NH 3 emission factor of 7% of total N in manure was defined for this system. These losses increased at higher ventilation rates and lower belt cleaning frequencies. Thus, NH 3 mitigation strategies at housing level should consider both parameters. Further studies would be necessary to determine how these factors regulate NH 3 emission at laying hen houses.