Ammonia, Nitrous Oxide, Carbon Dioxide and Methane Emissions from Commercial Broiler Houses in Mediterranean Portugal

Limited data are available on ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emissions from poultry housing in Mediterranean countries. The aim of the present study was to assess the NH3, N2O, CO2 and CH4 emission rates from commercial breeding hen and broiler houses under Mediterranean climate conditions. Research was conducted at one commercial breeding hen house and in two commercial broiler houses located in central Portugal. The environmental conditions, gas concentrations and ventilation rates were measured in the cold (8.0 +/- 2.1 degrees C) and hot (20.7 +/- 1.9 degrees C) season for the breeding hen house, whereas for the two broiler houses, measurements were made during one fattening cycle in the fall (17.3 +/- 1.7 degrees C) season. Results showed that the annual average emission rates for breeding hen and broiler houses were 0.52 +/- 0.27 and 0.06 +/- 0.01 for NH3, 0.030 +/- 0.042 and 0.006 +/- 0.001 for N2O, 169.6 +/- 56.2 and 58.0 +/- 15.1 for CO2 and 0.092 +/- 0.131 and 0.0113 +/- 0.0002gday(-1) bird(-1) for CH4, respectively. The N2O emission rates observed in breeding hen houses may have been overestimated, being higher than previously reported for Mediterranean countries.