Assessment of ammonia and greenhouse gas emissions from broiler houses in Portugal

Broiler husbandry is a significant source of ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emissions but scarce studies have been made under Mediterranean conditions. The aim of this study was to evaluate the NH3, N2O, CO2 and CH4 emissions on commercial broiler houses under Portuguese winter conditions. The study was made on a commercial broiler farm located in central Portugal. Three tunnel ventilated broiler houses with similar equipment and production practices were selected. The outdoor and indoor environmental conditions, gas concentrations and ventilation rates of each broiler house were measured during 42 days of growing cycle. Results showed that the maximum concentrations of NH3, N2O, CO2 and CH4 did not exceed the threshold values recommended to maintain indoor air quality on broiler houses. The average emission rates from broiler houses under winter conditions were 0.13 ± 0.04, 0.041 ± 0.002, 96.2 ± 8.8 and 0.226 ± 0.013 g day−1 bird−1 (22.0 ± 7.3, 6.7 ± 0.3, 16,028 ± 1465 and 37.7 ± 2.1 g day−1 LU−1) for NH3, N2O, CO2 and CH4, respectively. Furthermore, NH3 and N2O emission rates of this study are in the same range than measurements from most European countries, but CH4 emission rate seems higher to those reported for Mediterranean countries.