Since 2013, in EU, gestating sows are housed in groups. Even with automatic feeders, depending on individuals (i.e. age, hierarchy, weight) or groups (i.e. number of sows per feeder) characteristics, sows spend time and energy accessing feed which might modify their nutrient requirements, due to changes in their physical activity. The aim of this study was to evaluate the impact of an induced feed competition on the activity and social behaviour of gestating sows. A feed competition was set up by closing during 5 days (test period) one of the two feeders available in a pen housing 15 sows on average, doubling the number of sows per feeder. The previous week with the two feeders opened served as control (basal period). A total of 31 sows were included in the experiment. Skin lesions were visually recorded every week. Feeding behaviour was automatically recorded by the feeders. Videos recordings allowed to manually identify different behaviours: position, occupation, location in the room, and social interactions. The influence of the period (basal vs test) and parity (primiparous vs multiparous) on these measurements was analysed on R applying a linear mixed-effects model taking into account the random effect of the sows. The behaviour of the sows was impacted by the feed competition. During the first 36-h of test period, the number of visits to the feeder without receiving feed decreased compared to the basal period (2.3 vs 4.7 visits/d, P<0.01) while the number of visits with feed was not affected by period (1.1 visit/d). During the test period, the sows were waiting more in front of the feeder than during basal period (98.5 vs 40.1 min/d, P<0.01). Despite the increased number of negative social interactions during the test period (i.e. head shots, bites, P<0.01), there were no significant effect on the number of skin lesions. These results show that sows were more active and express more negative social interactions during a feed competition test. It can be calculated that this resulted in about 5% increase of their energy requirement. The number of sows per feeder is thus an important parameter to consider for improving gestating sows’ welfare and calculating their energy requirements.