Measurements of emission factors from a naturally ventilated commercial barn for dairy cows in a cold climate

•The DeLaval activity monitoring system has a high spatial and temporal resolution.•Emission factors of CH4, NH3, and N2O were measured from a commercial dairy barn.•Modelled enteric CH4 emission factor was 312 g CH4 head−1 day−1.•Enteric fermentation accounted for about 81% of the total CH4 emission.•Indoor manure accounted for up to 73 g CH4 head−1 day−1 (60 g CH4 LU−1 day−1).

Emission rates of CH4, N2O and NH3 were measured in a commercial free-stall barn that housed 141 lactating dairy cows, and 75 dry cows and replacement heifers. Animal activity, measured using the ALPRO™ dairy herd management system was used together with the CO2 balance method to calculate the ventilation rate. Methane emission was also modelled using the IPCC Tier 2 method. Animal activity variations similar to reported patterns indicated that the activity monitoring system provided high resolution measurements since all cows were considered. Diurnal variations were observed in the emissions with mean values of 12.2–13.9 g CH4 LU−1 h−1, 0.43–0.64 g NH3 LU−1 h−1 and 29.4–41.3 mg N2O LU−1 h−1. Modelled enteric CH4 emission was 312 g CH4 head−1 d−1 (10.58 g CH4 LU−1 h−1). It was estimated that indoor manure emitted 73 g CH4 head−1 d−1 (2.5 g CH4 LU−1 h−1), with enteric fermentation representing 81% of the total barn CH4 emission. Lactating cows emitted about 363 g CH4 head−1 d−1 (11.42 g CH4 LU−1 h−1) while non-lactating cows emitted 241 g CH4 head−1 d−1 (9.67 g CH4 LU−1 h−1).