A simplified method of measuring greenhouse gas and ammonia emissions in pig grower-finisher barns

Levels of GHG and ammonia emissions can be determined by continuously measuring concentrations in barn rooms during the entire fattening period. However, the high investment of time and money required by this method limit its widespread application; practically, it would be difficult to justify its use to assess the variability in emissions attributable to housing system, farming practices and climate in a large number of facilities. A simpler and reliable method was needed to assess the variability and develop appropriate mitigation strategies. With that objective in mind, and for two consecutive seasons, NH3, N2O, CO2, CH4 and water vapor were continuously measured during the entire fattening period. The pigs were reared from 30 to 110 kg on a fully slatted floor. To help validate the simplified method, a comparison of emissions measured in both batches with the nitrogen and carbon mass balances deficit was achieved and showed that 85 and 105% of total nitrogen and carbon losses were explained by measured gaseous emissions. Based on the emission kinetics obtained during continuous measurements, emissions were calculated using the concentrations ratios method. This method was based on carbon losses deduced from carbon mass balance combined with mean gas concentrations ratios obtained with spot measurements during the rearing period. Finally, results showed that intermittent gas concentrations measurements performed between 10 a.m. and 16 p.m. on days 25, 60 and 80 of fattening led to estimates of emission levels with an error less than 20%. Additional batches were used to validate this simplified method.