120 pigs fed the same diet (in 2 stages, growing and finishing) have been divided equally in 3 different groups for their growing-finishing stage and placed in 3 different rooms. In the room 1 the ventilation rate was 1500m3/h and the manure was stored under the slat during all the experiment, in the room 2 the ventilation rate was also 1500m3/h and the manure was removed every 40 days and in room 3 the ventilation rate was 750 m3/h and the manure was stored. Air samples were taken in the 3 rooms the day after the manure had been removed in the room 2 and were analyzed to evaluate the concentration of some odorants compounds (chemical analysis) and the odour emission (olfactometry). The nitrogen compounds were the main compound group identified in the analysis: ammonia, aldehydes and ketones were present at low concentrations. The analysis showed that the concentration of nitrogen compounds and aldehydes were lower for the room where the manure wasn’t stored under the slats. A reduction of 55% of the odor emission (odor rate) was measured when the manure is not stored for identical ventilation rates (room 2 vs. room 1). The room 3 was compared to room 1 (same manure management, half the ventilation rate in room 3 compare to room 1) showing that the ammonia and aldehydes concentration levels were lightly higher in room 3 and that the odor emission from room 3 was 29% lower than the one in room 1.

This experiment is interesting but no replicates were done to assure the validity of the results. Also it becomes a bit confusing because the results analysis are presented in term of concentrations for the chemical compounds and in term of production rate in term of odour which are 2 different things, the rate being the concentration multiplied by the ventilation rate. Even if the concentration is higher if the ventilation rate is low, the emission rate can be lower. The emissions in this case don’t give an exact information on the inside conditions.