Résumé : [en] A study was carried out to investigate the effect of dietary fibre content (23% of non-starch polysaccharides (NSP) with a standard diet based on cereals vs. 44% of NSP with a fibrous diet based on sugar beet pulp) and the floor type (slatted floor vs. straw-based deep litter) on emissions of ammonia (NH3), nitrous oxide (N2O), methane (CH4) and CO2-equivalents (Eq-CO2). Six successive batches of 10 gestating sows were divided into 2 groups kept in 2 experimental rooms differing by the floor type. The standard diet was administered to the sows of the first 3 batches, the fibrous diet to the sows of the next 3 batches. Emissions were measured by infra-red photoacoustic detection. With the slatted floor, the fibrous diet decreased NH3 emission (12.0 vs. 15.5 g sow-1.d-1) but increased the Eq-CO2 emissions (0.69 vs. 0.57 kg sow-1.d-1) in relation to an increase of CH4 emissions (18.4 vs. 12.8 g sow-1.d-1), the N2O emissions not being impacted by the diet, with value around 0.62 g sow-1.d-1. With the straw-bedded floor, the fibrous diet increased the emissions of NH3 (12.3 vs. 9.2 g sow-1.d-1) and CH4 (14.6 vs. 9.6 g sow-1.d-1) but decreased N2O emissions (0.99 vs. 1.64 g/ sow-1.d-1) with the consequence that Eq-CO2 emissions were similar for the two diets, around 0.74 kg sow-1.d-1.