Precision feeding (PF) aims at providing the right amount of nutrients at the right time for each animal. Lactating sows generally receive the same diet, which either results in insufficient supply and body reserve mobilization, or excessive supply and high nutrient excretion. With the help of online measuring devices, computational methods, and smart feeders, we introduced the first decision support system (DSS) for lactating sows PF. Precision (PRE) and conventional (STD) feeding strategies were compared in commercial conditions. Each PRE sow received each day a tailored ration, computed by the DSS. This ration was obtained from the blend of a diet with high AA and mineral contents (13.00 g/kg SID Lys, 4.50 g/kg digestible P) and a diet with low contents (6.50 g/kg SID Lys, 2.90 g/kg digestible P). All STD sows received a conventional diet (10.08 g/kg SID Lys, 3.78 g/kg digestible P). Before the trial, the DSS was fitted to farm performance for the prediction of piglet average daily gain (PADG) and sow daily feed intake (DFI), with data from 1,691 and 3,712 lactations, respectively. Sow and litter performance were analysed for the effect of feeding strategy with ANOVA, considering statistical significance when P<0.05. The experiment involved 239 PRE and 240 STD sows. DFI was high and similar in both treatments (PRE: 6.59, STD: 6.45 kg/d; P=0.11). Litter growth was high (PRE: 2.96, STD: 3.06 kg/d), although slightly decreased by about 3% in PRE compared to STD (P<0.05). Sow body weight loss was low, although slightly higher in PRE sows (7.7 vs 2.1 kg, P<0.001), which might be due to insufficient AA supplies in some sows. Weaning to oestrus interval (5.6 d) did not differ. SID Lys intake (PRE: 7.7, STD: 10.0 g/kg; P<0.001) and digestible P intake (PRE: 3.2, STD: 3.8 g/kg; P<0.001) were reduced by 23% and 14% in PRE sows and feed cost by 12%. Excretion of N and P were reduced for PRE sows by 28% and 42%, respectively. According to these results, PF appears to be a very promising strategy for lactating sows.