Favourable social behaviour between pigs is important and desirable for animal welfare,economic benefits to farmers, and human society. Already shown to be effective is geneticselection using social breeding values (SBVs). SBVs is the genetic effect based on the growthand behaviour of an individual on its pen mates Pigs with high SBV have desirable behaviourand cause less tail damage to their pen mates. It is further desirable to have a more clearunderstanding of the biological mechanisms behind animal behaviour. It is known thatmetabolites such as serotonin, influence behaviour. However, the relationship betweenbehaviour and metabolites is not yet well understood in pigs. If metabolites are heritable in pigs,combining the knowledge genomics and metabolites might result in more accurate predictionof behaviour. Therefore, this study contributes to the knowledge on genetics of behaviour inpigs. Six metabolites were measured on 480 genotyped animals housed in equal numbers inbarren and enriched housing. Behaviour was measured through video recordings. Amongthe six metabolites, the concentration of haptoglobin and IgG were affected by the housingsystems. In addition, SBV was significantly associated with haptoglobin and lymphocytes. Theheritability estimates using genomic information for haptoglobin, leukocytes, lymphocytes,serotonin, IgG, and IgM were 0.15, 0.26, 0.14, 0.21, 0.27, 0.41, respectively, which implies thatthese metabolites have a good genetic basis. There was a significant effect of SBV, haptoglobin,and IgM on tail damage as victim of undesirable behaviour. However, there was no significantcorrelation between the six metabolites and tail biting behaviour as perpetrator. Further dataanalysis is underway to investigate the usefulness of over 100 metabolites to reduce the riskof some undesirable behaviours like tail biting and for overall enhancement of pig behaviourand welfare.