1f:T537,Early life socialization of piglets has been shown to reduce piglet aggression at weaning, but information on sow health and long-term benefits is lacking. We aimed to assess how socialization impacts sow udder quality and long-term pig behaviour and growth. At two weeks of age, 65 litters either experienced socialization with one other litter (SOC) or did not (control; CON). Sows (housed in farrowing crates) were scored for teat damage and piglets were observed for aggressive behaviour (resident-intruder test) and growth and skin lesions up to 11 weeks under conventional farm conditions (including weaning and regrouping). At weaning, SOC sows had more teat damage than CON sows (p = 0.04). SOC piglets had double the number of lesions 24 h post-socialization compared to the control (19 versus 8; p < 0.001). In the resident-intruder test, more SOC pigs attacked the intruder (SOC 78%; CON 66%; p < 0.01), and attacked more quickly (p = 0.01). During regrouping (week 8), SOC pigs had 19% fewer lesions (SOC 68; CON 84; p < 0.05), but three weeks later, groups did not differ. Growth was unaffected by treatment. Overall, socialized piglets seem to be equipped with greater confidence or agonistic skills, leading to fewer injuries from fighting up to at least six weeks after socialization.20:T478,The purpose of this study was to determine how increasing the frequency of co-mingling affected piglets' behavior development before and after weaning. Co-mingling once (CM1), piglets interacted with 1 unfamiliar litter Days 10-18 after birth; co-mingling twice (CM2), piglets interacted with 1 unfamiliar litter Days 10-14; and with another, Days 14-18. Control (CM0) piglets did not interact with unfamiliar litters before Day 18 (n = 16 litters per treatment). The study weighed piglets and recorded ear-injury scores throughout the experiment; however, there were no treatment differences. The CM2 piglets spent less time engaged in aggressive interactions (p < .05) than did CM0 piglets following mixing at weaning. During the social challenge, CM2 piglets spent more time in proximity to one another, had shorter latencies to first aggressive interaction, and spent less time fighting than did CM0 piglets (p < .05). During the social recognition test, CM2 piglets recognized the stimulus piglet at a faster rate than did CM0 piglets (p < .05). Overall, CM2 resulted in changes to some social behaviors compared with CM0 but not with CM1.

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