Operationalising social competence and estimating its genetic and genomic basis to improve the welfare of pigs

摘要全球每年有10亿头猪被宰杀，大多数猪的福利因有害的社会行为而减少(例如，10%的猪因打架而被抓伤100多处，咬尾巴可能导致尾巴截肢和脊髓脓肿)。针对这些行为的管理解决方案成本高昂，限制了它们的实施。有害的社会行为是猪福利面临的最持久和最常见的挑战之一。然而，猪在给予和接受有害行为的数量上有所不同。这种变异有遗传因素，防止有害行为表达的育种可以极大地提高福利和生产力。然而，在孤立的有害行为特征上繁殖是低效的，因为它可能会恶化其他特征。它也没有考虑到积极的社会互动可能在功能性社会关系中发挥的潜在重要作用，而到目前为止，这种作用在很大程度上被忽视了。这个项目采用了一种新的方法，通过探索繁殖的潜力来培养整体的社会能力。在行为生态学中，社交能力是一种更高层次的特征，它来自于社交技能和改善健康的行为(即生存和繁殖成功)的结合。因此，一种有社交能力的动物是指其组合的社交行为使其适应能力最大化的动物。至关重要的是，这一概念允许积极和消极的行为形式影响整体的社会能力。此外，它不仅仅是一个单独的行为清单，而是考虑到行为特征之间的关系，以考虑它们对健康的综合影响。有证据表明，除了构成社会能力的个人行为外，社会能力还受到自然选择的影响。该项目将社会能力的概念新颖地应用于受管理的动物。它将检验两个假设：(I)社会行为特征可以被整合起来，以定义通过其对福利的影响来识别的新兴社会能力，以及(Ii)社会能力受到基因控制，可以在动物育种中加以利用。我们的目标是创造新的基础知识，并为养猪业提供一种定义、测量和繁殖猪的方法，使猪具有全面的社会能力，证明对福利有好处。PIC是世界上最大的猪饲养商，也是该项目的合作伙伴，该项目将确保快速将结果转化为商业成果。目标1在SRUC的猪研究农场，通过让一半的猪在断奶前获得更多的社会经验，最大限度地提高社交能力的可能性。接下来，我们将在不同的环境中饲养猪，并测量广泛的社会行为和福利结果。统计模型将描述社会行为如何结合在一起，以解释福利结果的最大差异，从而说明哪些行为套件定义了社会能力。目标2将在SRUC单位和PIC养殖场进行，这两个养殖场的环境不同，但将使用相同的父系。将记录目标1中显示的构成社会能力的社会行为。这将量化(I)遗传对社会能力的决定，(Ii)环境对遗传倾向表达的影响，以及(Iii)为提高社会能力而进行繁殖的经济结果。社交能力在任何物种中都没有得到很好的描述，我们希望我们对这一概念的新颖使用会引起广泛的兴趣。它将加强对行为如何相互作用以及积极社会行为在福利中的作用的理解，人们对此知之甚少。繁殖出理想的行为组合的可能性，包括亲社会的行为，从未被研究过。让养猪业具备繁殖的能力，使其能够有效地结合几种社会行为的交互影响，并明显改善福利，可能会使大多数商业化生产的猪受益。

SummaryGlobally one billion pigs are slaughtered annually and most experience reduced welfare from harmful social behaviours (e.g. 10% of pigs gain more than 100 scratches from fighting and tail biting can cause tail amputation and spinal abscesses). Management solutions to these behaviours are costly which limits their implementation. Harmful social behaviours are one of the most persistent and routine challenges to pig welfare. However, pigs differ in the amount of harmful behaviour they give and receive. There is a genetic contribution to this variation and breeding against expression of harmful behaviours could greatly improve welfare and productivity. However, breeding on isolated harmful behavioural traits is inefficient as it could worsen other traits. It also fails to account for the potentially major role that positive social interactions may play in functional social relationships that has so far largely been ignored. This project takes a new approach by exploring the potential to breed for overall social competence. In behavioural ecology, social competence is a higher level trait that emerges from the combination of social skills and behaviours that improve fitness (i.e. survival and reproductive success). A socially competent animal is therefore one whose combined social behaviour maximizes its fitness. Crucially, the concept allows positive and negative forms of behaviour to affect overall social competence. Additionally, it is more than simply a list of isolated behaviours, but instead accounts for the relationships between behavioural traits to consider their combined effect on fitness. There is evidence that social competence is under natural selection, in addition to those individual behaviours that comprise it. This project makes a novel application of the social competence concept to managed animals. It will test two hypotheses that (i) social behavioural traits can be integrated to define emergent social competence identifiable by its effects on welfare and (ii) that social competence is under genetic control that can be exploited in animal breeding. Our aim is to both create new basic knowledge and to practically equip the pig breeding industry with a way to define, measure and breed for pigs with an overall social ability that has evidenced benefits for welfare. PIC is the largest pig breeder in the world and a partner in this project which will ensure rapid commercial translation of the results.Objective 1 on SRUC's pig research farm will maximise likely variation in social competence by giving half of the pigs increased social experience before weaning. Next we will house pigs in contrasting environments and measure a broad range of social behaviours and welfare outcomes. Statistical modelling will describe how social behaviours combine to explain maximum variation in welfare outcomes and hence which suites of behaviours define social competence. Objective 2 will occur at the SRUC unit and a PIC breeding farm which differ in environments but will use the same sires. The social behaviours shown in Objective 1 to constitute social competence will be recorded. This will quantify (i) the genetic determination to social competence, (ii) the effect of the environment on expression of genetic predisposition, and (iii) the economic outcomes of breeding for enhanced social competence. Social competence has been poorly characterised in any species and we expect our novel use of the concept to be of broad interest. It will enhance understanding of how behaviours interact and the role of positive social behaviours in welfare, of which very little is known. The potential to breed for desirable combinations of behaviours, including pro-social ones, has never been studied. Equipping industry with the ability to breed for a trait that efficiently combines the interactive effects of several social behaviours and that demonstrably improves welfare could benefit the majority of commercially produced pigs.