Cho Andrew Inhyuk, Lee Caroline, Small Alison
CSIRO Agriculture & Food, Commonwealth Scientific and Industrial Research Organisation, Armidale, NSW, Australia.
School of Veterinary Science, University of Melbourne, Melbourne, VIC, Australia.
PeerJ. 2020 Oct 6;8:e10081. doi: 10.7717/peerj.10081. eCollection 2020.
The social context of social species such as sheep can modify their physiological and behavioural responses to stressors, through social buffering and social facilitation. Social buffering can lead to amelioration of stress, while social facilitation can lead to stress responses in an observer animal in the presence of a conspecific in distress. The current study investigated twin lambs undergoing ring castration, grouped either homogeneously with a castrated lamb (actor), or heterogeneously with a non-castrated lamb (observer) to examine the impact of social grouping on behavioural responses. Each lamb was scored for two classes of behaviour: pain-related behaviours and postures that are putatively related to the response to castration; and attentional behaviours directed at its twin. Thus, each lamb participated in the experiment as an actor exhibiting pain-related behaviours and postures, and as an observer of its twin. When behaviours of lambs were assessed as actors, there was a significant ( < 0.05) effect of castration but no significant effect of social grouping on expression of pain-related behaviours. When behaviours of lambs were assessed as observers, homogeneous grouping of castrated lambs increased attention towards the other twin in comparison to non-castrated lambs grouped homogeneously or lambs grouped heterogeneously ( < 0.01). Non-castrated lambs grouped homogeneously demonstrated significantly lower numbers of head direction changes ( < 0.001) and lower number of ear posture changes ( < 0.05) than heterogeneously grouped or castrated lambs. This study indicates that social attention between twin lambs is not clearly dependent on pain status of the actor lamb. It suggests that in order for the observer lamb to provide significant attention to the actor lamb displaying pain-related behaviour, the observer lamb also needs to be experiencing pain concurrently. Furthermore, there is some evidence that the presence of pain-related behaviours can lead to increased attention to the surrounding environment in non-castrated lambs. Understanding the effect of concurrent experience and varying social context assists us to improve our understanding of results of other experiments on pain-related behavioural responses.
绵羊等群居物种的社会环境可通过社会缓冲和社会促进作用来改变其对压力源的生理和行为反应。社会缓冲可减轻压力，而社会促进则会使处于困境中的同种动物在场时，观察动物产生应激反应。本研究调查了接受环状阉割的双羔绵羊，将它们要么与一只阉割过的羔羊（行动者）同质分组，要么与一只未阉割的羔羊（观察者）异质分组，以检验社会分组对行为反应的影响。每只羔羊都针对两类行为进行评分：与疼痛相关的行为和姿势，这些行为和姿势被认为与对阉割的反应有关；以及针对其双胞胎的注意力行为。因此，每只羔羊都作为表现出与疼痛相关行为和姿势的行动者，以及其双胞胎的观察者参与实验。当将羔羊的行为作为行动者进行评估时，阉割有显著（<0.05）影响，但社会分组对与疼痛相关行为的表达没有显著影响。当将羔羊的行为作为观察者进行评估时，与同质分组的未阉割羔羊或异质分组的羔羊相比，阉割羔羊的同质分组增加了对另一只双胞胎的关注（<0.01）。与异质分组或阉割羔羊相比，同质分组的未阉割羔羊头部方向变化的次数显著更少（<0.001），耳朵姿势变化的次数也更少（<0.05）。这项研究表明，双羔绵羊之间的社会关注并不明显取决于行动羔羊的疼痛状态。这表明，为了使观察羔羊对表现出与疼痛相关行为的行动羔羊给予显著关注，观察羔羊也需要同时经历疼痛。此外，有一些证据表明，与疼痛相关行为的存在会导致未阉割羔羊对周围环境的关注度增加。了解同时经历和不同社会环境的影响有助于我们更好地理解其他关于与疼痛相关行为反应实验的结果。
