Effects of Animal and Climate Parameters on Gas Emissions from a Barn for Fattening Pigs

Abstract

Increased knowledge of the factors that affect emissions from livestock barns may lead to a better understanding of daily (between different days) and diurnal (within a specific day) variations in emissions, an improvement of mitigation methods and a refinement of emission models. The influence of animal activity, animal weight, indoor air temperature and relative humidity on carbon dioxide, methane, and ammonia emissions was assessed on a daily and diurnal basis in a barn with three successive batches of fattening pigs. The floor was partly slatted, manure was removed daily, and the ventilation rate was fixed for each batch. Variations between the batches in mean methane emissions (0.33–1.62 g pig-1 h-1) were larger than the variations in the mean emissions of carbon dioxide (84–91 g pig-1 h-1) and ammonia (0.18–0.20 g pig-1 h-1). Animal weight explained most of the daily variations in carbon dioxide and ammonia emissions. Animal weight and indoor air temperature explained most of the daily variations in methane emissions. A regression analysis of methane emissions as a function of the indoor air temperature and animal weight explained 56% of the variations in the measured methane emissions. Animal activity decreased with increasing animal weight and air temperature. Diurnal variations in carbon dioxide and ammonia emissions were mainly affected by the animal activity, with correlation coefficients (r) of 0.89 and 0.68, respectively. Diurnal variations in methane emissions only slightly correlated with the animal activity (r = 0.41, p = 0.05). Emission variations emphasized the need for measurements during different times within the day and during the growing period in order to obtain reliable data for assessing abatement techniques.