Mixing gestating sows implies hierarchy formation and has detrimental consequences on welfare. The effects of social stress on the most vulnerable individuals may be underestimated and it is therefore important to evaluate welfare between individuals within groups. This study aimed at investigating the impact of social status and previous experience in the group on well-being of sows housed in large semi-static groups (20 groups of 46-91 animals). We assessed aggression (d0 (mixing), d2, d27, d29), body lesions (d1, d26, d84) and feeding order. Social status was based on the proportion of fights won during a 6-hr observation period between d0 and d2. Dominants (29%) were those who won more fights than they lost, Subdominants (25%) won fewer fights than they lost, Losers (23%) never won any fight in which they were involved while Avoiders (23%) were never involved in fights. Resident sows (70%) were already present in the group in the previous gestation while New sows (30%) were newly introduced at mixing. Subdominants and Dominants were highly involved in fights around mixing but this was more detrimental for Subdominants than Dominants, Losers and Avoiders since they had the highest body lesion scores at mixing. Avoiders received less non-reciprocal agonistic acts than Losers on d2 ( P =0.0001) and had the lowest body lesion scores after mixing. However, Avoiders and Losers were more at risk in the long-term since they had the highest body lesions scores at d26 and d84. They were followed by Subdominants and then Dominants. New sows fought more ( P <0.0001), tended to be involved in longer fights ( P =0.075) around mixing and had more body lesions throughout gestation than Resident sows. Feeding order from one-month post-mixing was influenced both by the previous experience in the group and social status ( P <0.0001). New sows, especially with a low social status, are more vulnerable throughout gestation and could serve as indicators of non-optimal conditions.

中文翻译：

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该群体的社会地位和以前的经验可以预测大型半静态群体中母猪的长期福利

混合妊娠母猪意味着等级制度的形成，对福利产生不利影响。社会压力对最弱势个体的影响可能被低估了，因此评估群体内个体之间的福利很重要。这项研究的目的是调查该群体的社会地位和以前的经验对大型半静态群体（20组，每组46-91只动物）中母猪的健康状况的影响。我们评估了攻击性（d0（混合），d2，d27，d29），身体病变（d1，d26，d84）和喂养顺序。社会地位基于在d0至d2之间的6小时观察期内赢得的打架比例。优势（29％）是赢得胜利多于失败的人；次要优势（25％）是赢得失败多于失败的人，失败者（23％）从未赢得过他们所参与的战斗，而回避者（23％）从未参与过战斗。该组在先前的妊娠中已经有母猪（70％），而混合时新引入了新母猪（30％）。次要优势者和主导者在混合方面的战斗中参与度很高，但这对次要优势者比优势者，失败者和回避者更为有害，因为它们在混合时具有最高的身体病变分数。回避者在d2上接受的互惠激动行为少于失败者（P = 0.0001），并且混合后的身体病变得分最低。但是，长期而言，回避者和失败者的风险更高，因为它们在d26和d84时的身体病变评分最高。其次是次要优势，然后是优势优势。新母猪的战斗更多（P <0.0001），往往比混合母猪参与更长的战斗（P = 0.075），并且在整个妊娠过程中比常驻母猪有更多的身体损伤。混合后一个月的喂食顺序受该组以前的经验和社会地位的影响（P <0.0001）。新母猪，特别是社会地位低的母猪，在整个妊娠过程中更容易受到伤害，并且可以作为非最佳状况的指标。