A simplified method to assess greenhouse gas and ammonia emission factors of fattening pigs reared on fully slatted floor

Measurements of greenhouse gases and ammonia emissions can be performed by measuring continuously concentrations in rooms during the whole rearing period. Nevertheless, time and cost relative to this method limit the application to a large number of facilities and is not appropriate to assess the variability of emissions in relation to housing systems, farmer practices and climate. In order to border this variability and to identify mitigation strategies, simplified methods have to be developed. To do so, during winter 2006 and summer 2007, NH3, N2O, CO2, CH4 and, H2O emissions from fattening pigs were measured continuously during the whole rearing period. Pigs were fattened between 30 and 100 kg and kept on fully slatted floor. For validation, a comparison of measured emissions for both batches with the nitrogen and carbon mass balances deficits showed that 85 and 105 % of total nitrogen and carbon losses were explained by measured gaseous emissions. Based on the emissions kinetics obtained during continuous measurements, emissions were calculated using the concentrations ratios method. This method is based on carbon losses deduced from carbon mass balance combined with mean gas concentrations ratios obtained with spot measurements during the rearing period. Results showed that intermittent gas concentrations measurements performed during 4 hours in the afternoon on days 24, 60, 80 allow the assessment of emissions factors with an error lower than 20%.