An appreciation of odour (as no measures are presented) showed that the sawdust bedding produced lower odour nuisance compared to straw litter and that the aerated litter also produced less odours. The pig performances showed no negative effect from the deep litter system. More work has to be done to find the optimum conditions for the good composting and nitrification and denitrification process that lower the NOx emissions as this system present advantages in reducing odour nuisance and improving the animal welfare.