Gaseous emissions from deep-litter pens with straw or sawdust for fattening pigs

Three successive batches of fattening pigs were raised on a deep litter of straw in one room and of sawdust in another. The quantities of litter used per pig were 40 kg of straw and 81 kg of sawdust. Once a month, the emissions of ammonia, nitrous oxide, methane, carbon dioxide and water vapour were measured continuously for 6 days consecutively. Gaseous emissions from pig raising on sawdust-based litter and straw-based litter were respectively 12.16 and 13.61 g per pig per day for ammonia (NH3), 4.96 and 7.39 g per pig per day for methane (CH4), 2.09 and 0.03 g per pig per day for nitrous oxide (N2O), 3.15 and 2.74 kg per pig per day for water (H2O) and 1.32 and 1.30 kg per pig per day for carbon dioxide (CO2). Differences between the emissions of the two litters were significant for N2O and H2O (P < 0.01). The nitrogen content of the manures collected at the end of the experiment was 1.47 kg per pig for the straw-based litter and 1.07 kg per pig for that based on sawdust. Nitrogen emissions were calculated under the assumption that no gases volatilized from the litter or from the animals other than NH3 and N2O. With the two litters, about 50% of nitrogen excreted by the pigs was emitted into the atmosphere in the form of N-2.