Ammonia, nitrous oxide, methane, carbon dioxide and water vapour emissions in a fattening pig house on deep litter: levels of production and correlation with pigs activity

During a 4-month fattening period, emissions of NH3, N2O, CH4, CO2 and H2O from a pig house with fattening pigs on deep litter was measured once a month during four days (one measurement every 30 min). The activity rate of the animals was also measured hourly as the mean proportion of standing animals observed each two minutes. The mean daily emissions of gas, calculated per pig, were 9,5 g NH3, 3,2 g N2O, 4,8 g CH4, 1,3 kg CO2 and 3,3 kg water vapour. Emissions increased during the fattening period, the values observed at the end being 50%, 50%, 680% and 1000% higher than those at the beginning, for CO2, H2O, CH4 and NH3 respectively. Emissions of N2O were however higher at the beginning than at the end of the fattening period. The activity rate of the pigs followed a circadian rhythm, pigs being observed in a standing position much more frequently during the day than during the night, especially in the morning, at the end of the afternoon and at the beginning of the evening. The activity rate decreased continuously during the fattening period, from 22,6 +/- 4,1% to 8,8 +/- 0,5%. Within each monthly observation period, the hourly emissions of NH3, CO2 and H2O were positively correlated with the pigs' activity rate, the mean correlation coefficients being 0,61 for NH3, 0,71 for CO2 and 0,75 for water vapour. The correlation coefficients were not significant for N2O and CH4 in periods 2 et 3 but significant in periods 1 and 4 with mean values of -0,55 for N2O and +0,26 for CH4