Two different techniques, straw bale odour filter and deep litter of sawdust or straw were verified to evaluate their ability to minimize odour and slurry production. Two fattening periods of 21 and 19 weeks were done with 2 lots of 15 pigs to test first a 50 cm deep sawdust litter and then a 80 cm deep unchopped barley straw litter and both cycles were compared to the performances of 2 lots of 16 pigs housed on partly-slatted floor (control group). The air coming from the control section was filtered with a biofilter house made out of straw bales. The straw bale biofilter was effective in decreasing the pig smell by 50% and the deep litter were effective in controlling odour and reducing the slurry production.

The experiment done on a small scale give interesting results for the biofilter. Not enough information is given to judge on the odour reduction obtained with the deep litters. The use of a large scale biofilter is not address so it is difficult to evaluate of its capacities in reducing odour from whole swine building.