Characterisation of odorous compounds and emissions from slurries produced from weaner pigs fed dry feed and liquid diets

Changes in odorous emissions were recorded from slurries produced by weaner pigs fed dry feed and feed with water added in the respective ratios of 3:1 and 4:1. Slurries were placed in an environmentally controlled emissions chamber, periodic air sampling was performed to determine the olfactometric response as odour concentration, and the air was analysed to identify volatile organic compounds present. Distinctive odours were produced by each slurry. However, four major groups of odorants were identified as sulphides, volatile fatty acids, phenols and indoles. The odour concentration from the slurry of the 4:1 diet was significantly less (P < 0.05) than the odour concentration from the dry feed and 3 :1 slurry samples. Decay of the sulphide component of the odours was investigated and the role of methanogenesis in reducing odour production is discussed. While monitoring the emissions in the chamber the slurry odorant concentrations increased by up to 50 ppm h(-1).