Institute of Animal Welfare Science, University for Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria; Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Ul. Postępu 36a, 05-552 Jastrzębiec, Poland.
Institute of Animal Welfare Science, University for Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
Animal. 2023 Jun;17(6):100846. doi: 10.1016/j.animal.2023.100846. Epub 2023 May 5.
Farm animals can form preferential associations within their social group. Research has shown that the presence of familiar conspecifics can help to cope with stressful situations. Nonetheless, whether the strength of the relationship matters is largely unknown. Our aim was to investigate the influence of the strength of the social relationship between familiar partners during a stressful event. Pigs (n = 116) were observed pre-weaning for their social interactions and spatial proximity with littermates. From this, preferential associations were calculated based on sociality indices of non-agonistic social behaviours (SI) and spatial proximity (SI). Pigs were weaned into groups of unfamiliar pigs together with one littermate. The partner was selected based on the strength of their relationship pre-weaning, with pairs from across the SI and SI distribution. SI and non-agonistic social behaviour (SI) were included in the statistical analysis as measures of relationship strength. Focal pigs were observed postweaning for their social behaviour and spatial proximity, skin lesions and growth, and salivary cortisol concentration pre-weaning and at 4 h and 48 h postweaning. The strength of the social relationship pre-weaning did not significantly influence the behaviour or proximity towards the familiar partner postweaning, or the amount of skin lesions or weight gain. Pigs who were weaned with a littermate with whom they were strongly affiliated based on active social behaviour (SI) tended to have a lower proportional increase in their cortisol concentration after weaning (P = 0.07). Pigs differed in their behaviour towards the familiar partner as compared to the unfamiliar pigs, by directing more aggression towards unfamiliar pigs (P < 0.001), and more non-agonistic social behaviours towards the familiar pig (P < 0.001). The familiar partner was on average in 12.2% of the observations the nearest neighbour, which in small groups did not differ from random choice while in large groups, this occurrence was higher than expected by chance. The results show that pigs clearly distinguish between familiar and unfamiliar pigs, but that the strength of the relationship with a familiar partner seems to have limited effects at weaning. Although preferential associations in young pigs seem weak, studies on older pigs are needed to investigate whether this is due to the relatively little time they have to establish social preferences prior to weaning.
农场动物可以在其社会群体中形成优先关系。研究表明，熟悉的同种动物的存在可以帮助它们应对压力环境。然而，关系的强弱是否重要在很大程度上尚不清楚。我们的目的是研究在压力环境下，熟悉伙伴之间社会关系强弱对动物的影响。在断奶前，我们观察了 116 头猪的社会互动和与同窝仔猪的空间接近程度，并基于非攻击性行为的社交性指数（SI）和空间接近程度（SI）来计算其优先关系。这些猪断奶后与不熟悉的猪一起被分到一组，与其中一只同窝仔猪一起。根据它们在断奶前的关系强弱选择伴侣，伴侣选择跨越了 SI 和 SI 分布。在断奶前和断奶后 4 小时和 48 小时，通过记录猪的非攻击性行为（SI）和行为来测量关系强度，并将其纳入统计分析。断奶后观察猪的社会行为和空间接近程度、皮肤损伤和生长情况，以及断奶前和断奶后 4 小时和 48 小时的唾液皮质醇浓度。断奶前的社会关系强弱并没有显著影响猪在断奶后的行为或与熟悉伙伴的接近程度，也没有显著影响皮肤损伤或体重增加的数量。基于积极的社交行为（SI），与同窝仔猪关系密切的猪在断奶后皮质醇浓度的比例增加较低（P=0.07）。与不熟悉的猪相比，猪对熟悉的猪的行为有所不同，它们对不熟悉的猪表现出更多的攻击性（P<0.001），对熟悉的猪表现出更多的非攻击性行为（P<0.001）。在平均 12.2%的观察中，熟悉的猪是最近的邻居，在小群体中，这种情况与随机选择没有区别，但在大群体中，这种情况的发生频率高于随机选择。结果表明，猪能够清楚地区分熟悉和不熟悉的猪，但与熟悉的猪的关系强弱在断奶时似乎影响有限。尽管幼年猪的优先关系似乎较弱，但需要对成年猪进行研究，以调查这是否是由于它们在断奶前建立社会偏好的时间相对较少所致。
