Ammonia and greenhouse gas emissions from a modern U.S. swine breeding-gestation-farrowing system

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Aerial emissions from livestock production continue to be an area of attention and concern for both the potential health and environmental impacts. However, information of gaseous, especially greenhouse gas (GHG), emissions for swine breeding/gestation and farrowing production systems is limited. The purpose of this study was to quantify ammonia (NH3), carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) concentrations and emissions from a modern breeding-gestation-farrowing system located in central Iowa, USA. A 4300-sow farm was selected for the extensive field monitoring which employed a Mobile Air Emission Monitoring Unit equipped with state-of-the-art gas analyzers and a data acquisition system. The monitored portion of the farm facility consisted of a deep-pit breeding/early gestation (B/EG) barn (1800 head), a deep-pit late gestation (LG) barn (1800 head), and two shallow-pit (pull-plug) farrowing rooms (40 head per room). A dynamic flux chamber was used to monitor gaseous emissions from the external manure storage for the farrowing rooms. Data were collected for 29 consecutive months (January 2011 through June 2013). Daily indoor NH3, CO2, N2O, and CH4 concentrations (ppm, mean ± SD) were 12.0 (±7.6), 1594 (±797), 0.31 (±0.11), and 28.5 (±9.8), respectively, in the breeding/gestation barns; and 9.7 (±4.1), 1536 (±701), 0.30 (±0.10), and 78.3 (±37), respectively, in the farrowing rooms. Daily emissions per animal unit (AU, 500 kg live weight) were 35.1 g NH3, 7.46 kg CO2, 0.17 g N2O, and 263.4 g CH4 for sows in the B/EG barn; and 28.2 g NH3, 6.50 kg CO2, 0.12 g N2O, and 201.3 g CH4 for sows in the LG barn. The average daily emissions per AU (sow and piglets) of the farrowing rooms during the lactation period (birth to weaning) were: 59.7 g NH3, 16.4 kg CO2, 0.73 g N2O, and 107 g CH4. For the monitored period, the external manure storage had the following average daily emission per m2 surface area: 1.26 g NH3, 137 g CO2, and 94.8 g CH4, which was equivalent to daily emissions per AU in the farrowing rooms of 12.2 g NH3, 1.055 kg CO2, and 867 g CH4. Average daily emissions per AU for the total operation (including house-level and manure storage emissions) were 38.5 g NH3, 8.73 kg CO2 (including 7.3 kg from animal respiration), 0.25 g N2O, and 301 g CH4.