The post-weaning aggression among piglets is a serious problem in modern pig production which compromises animal welfare and health, as well as could cause considerable economic losses. To prevent post-weaning aggression between piglets an approach of early socialisation of piglets during lactation was tested in the present study. In the group farrowing pen (GFP) three individual farrowing pens were interconnected whereby piglets had free access to move across pens and/or cross-suckled alien sows that were still individually crated – passage between pens was released within 24h postpartum. Piglets/litters in the control group went through the conventional breeding practice (i.e. individual farrowing pen/crate). Altogether, the experiment involved 235 piglets. The preliminary results revealed that the suckling order stability differed between studied breeding technologies (group and individual). About one third of all piglets (31.3%) were found being involved (at least once) in the cross-suckling, i.e. suckling by the alien mother. Consequently, suckling stability was found generally lower in the GFP, with a significant drop after two weeks of lactation. Regarding the growth performance, piglets from GFP grew relatively, i.e. considering initial body weight, faster both during lactation and after weaning, although their daily weight gain was not significantly higher. The present preliminary study revealed early socialisation of piglets as an effective method to mitigate post-weaning aggression, as well as to improve their growth performance. However, considering mortality in lactation and disturbances in suckling stability, additional studies are needed to optimize the process of early socialisation, particularly in terms of piglets’ age when grouping of non-littermates is implemented during lactation.