Gaseous emissions from weaned pigs raised on different floor systems

Gaseous emissions from agriculture contribute to a number of environmental effects. Carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) are greenhouse gases taking part to the global problem of climate change. Ammonia (NH₃) emissions are responsible of soil acidification and eutrophication and contribute also to indirect emissions of N₂O. This work evaluated the influence of the type of floor on the emissions of these gases in the raising of weaned pigs. Two trials were carried out. In the first trial, the animals were kept either on fully slatted floor or on straw-based deep litter and, in the second one, either on fully slatted floor or on sawdust-based deep litter. For each trial and on each type of floor, 2 successive batches of weaned pigs were raised without changing the litter or emptying the slurry pit between the 2 batches. The rooms were automatically ventilated to maintain a constant ambient temperature. The performance of the animals was not significantly different according to the floor type. In trial 1, the nitrogen contents of the straw deep litter (including the substrate) and slurry were respectively 276 and 389gpig⁻¹. In trial 2, the sawdust deep litter and slurry nitrogen contents were respectively 122 and 318gpig⁻¹. Raising pigs on straw deep litter produced proportionately around 100% more NH₃ than raising pigs on slatted floor (0.61g NH₃-Nd⁻¹ pig⁻¹ vs. 0.31g NH₃-Nd⁻¹ pig⁻¹; P <0.05). Differences in CO₂, H₂O and CH₄ emissions were not significant between systems. Raising pigs on sawdust deep litter produced also proportionately more NH₃ (+52%; 0.55g NH₃-Nd⁻¹ pig⁻¹ vs. 0.36g NH₃-Nd⁻¹ pig⁻¹; P <0.01) but also more CO₂ (+25%; 427gd⁻¹ pig⁻¹ vs. 341gd⁻¹ pig⁻¹; P <0.001) and H₂O (+65%; 981gd⁻¹ pig⁻¹ vs. 593gd⁻¹ pig⁻¹; P <0.001) and less CH₄ (-40%; 0.52gd⁻¹ pig⁻¹ vs. 0.86gd⁻¹ pig⁻¹; P <0.001) than raising pigs on slatted floor. Practically no N₂O emission was observed from rooms with slatted floor while the N₂O emissions were 0.03 and 0.32g N₂O-Nd⁻¹ pig⁻¹ for the straw and sawdust deep litter respectively. The warming potential of the greenhouse gases (N₂O+CH₄), were about 22, 34 and 168g CO₂ equivalents per day and per pig on fully slatted floor, straw or sawdust deep litter respectively. In conclusion, pollutant gas emissions from rearing of weaned pig seem lower with fully slatted plastic floor system than with deep litter systems.