Greenhouse gas emissions from swine barns of various production stages in suburban Beijing, China

Gaseous emissions from animal feeding operations may be influenced by production stage, genetics, dietary type and nutritional plan, housing type, manure handling schemes, and climatic conditions. This study was conducted to quantify annual emission rates (ERs) of greenhouse gases (GHGs)—methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) from naturally ventilated swine gestation (GE), farrowing (FA), nursery (NU) and growing-finishing (GF) barns under typical operational conditions in suburban Beijing, China. Variables relative to the GHG ERs were measured every two months for a one-year period, with each measurement episode lasting 72 h. Air exchange rate of the naturally ventilated barns was estimated using CO2 balance method. The annual mean daily GHG ERs (mean ± SD), expressed in (AU=animal unit=500 live body weight), for the GE, FA, NU, and GF barns were, respectively, and for CO2; 9.6±1.9,9.6±3.6,58.4±21.8 and 32.1±11.7 for CH4; and 0.75±0.56,0.54±0.15,1.29±0.37 and 0.86±0.75 for N2O. The GHG ER values from the current study paralleled those reported in the literature in some cases but differed considerably in other cases. This outcome of similarity and disparity confirms the need to exercise caution when applying literature data to estimation of GHG emissions under various production systems. Results of this study are expected to contribute to the global GHG inventory.