Understanding assessment strategies during aggressive encounters in pigs to improve welfare following regrouping.

了解猪在攻击性遭遇期间的评估策略，以改善重组后的福利。

• 批准号: BB/L000393/1
• 负责人: Simon Turner
• 金额: $ 56.83万
• 依托单位: Scotland's Rural College
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FL000393%2F1
• 关键词: Understanding; assessment; strategies; during; aggressive

Global demand for pig meat is increasing, with over one billion pigs slaughtered annually. Production has become increasingly intensive with most pigs in the UK and EU being raised indoors and reaching slaughter weight within 6 months. During this production cycle, regrouping of unfamiliar pigs is common practice, typically occurring several times during a pig's life. This sudden mixing of unfamiliar pigs represents a major animal welfare concern. The social structure of domestic pigs is based on a dominance hierarchy. In the wild, migration between social groups occurs gradually, and hierarchies are formed with minimal aggression. In contrast, when pigs are mixed into new groups (regrouped) under commercial conditions, dominance hierarchies are formed through vigorous fighting, with many pigs receiving 100 or more skin scratches caused by biting. This is stressful for pigs, resulting in injuries, increased risk of infection, and reduced weight gain. This proposal is aimed at addressing the problem of regrouping aggression in pigs. The information gathering and decision making processes used by pigs to resolve aggressive encounters are poorly understood. However, there is a large body of research on contest behaviour in numerous other animal species. This work has benefitted greatly from the application of theoretical models that are based on particular information gathering rules. Two classes of model have been developed that differ in the strategies used during contests. In the first class, termed self assessment, animals make fight decisions based purely on their own fighting ability and stamina, using internal cues and without reference to the fighting ability of an opponent. After a certain (threshold) amount of energy has been spent on fighting, the individual will give up, and the opponent with the lower threshold will be the loser. In the second class of model, termed mutual assessment, animals self assess but also use information about the fighting ability of an opponent. Although more complex, it has greater benefits as an animal can quickly withdraw from a fight it is likely to lose.Whether pigs settle fights using a self or mutual assessment strategy has major implications for the degree of escalation. With self assessment animals will always fight up to a threshold, whereas with mutual assessment the use of information about the opponent will allow the weaker animal to quickly abandon a fight it is likely to lose. By examining aggressive interactions between pairs of unfamiliar pigs and employing a suitable statistical framework, this proposal will identify the assessment strategy used.Similar to human personalities, pigs show individual differences in aggressiveness, with some individuals being more aggressive than others. How these differences influence fight outcomes and the types of assessment detailed above is currently unknown. This will be revealed using a technique to measure aggressiveness. Additionally, the importance of fight experience for developing mutual assessment ability will be examined by comparing pigs that have experienced regrouping in comparison to individuals with no prior fighting experience. An important aspect of this project is aimed at optimising the assessment abilities of pigs to minimise levels of aggression when regrouped. We will investigate whether socialising piglets during early life, by allowing adjacent litters to mix prior to weaning, equips pigs with the necessary skills for mutual assessment during aggressive encounters later in life. Finally, the above research outcomes will be translated to the regrouping situation. Group composition will be manipulated to optimise the capability of individuals for mutual assessment. This will facilitate hierarchy formation with minimal fighting. Achieving this objective and translating this knowledge to industry has the potential to improve the welfare of the vast majority of commercially produced pigs.

全球对猪肉的需求不断增加，每年屠宰超过十亿头生猪。生产变得越来越集约化，英国和欧盟的大多数生猪都在室内饲养，并在 6 个月内达到屠宰体重。在这个生产周期中，对不熟悉的猪进行重组是常见的做法，通常在猪的一生中会发生几次。这种不熟悉的猪的突然混合代表了一个主要的动物福利问题。家猪的社会结构基于统治等级。在野外，社会群体之间的迁移是逐渐发生的，等级制度是在最小的攻击性下形成的。相比之下，当猪在商业条件下混入新的群体（重新分组）时，通过激烈的战斗形成了统治等级，许多猪因咬伤而被抓伤100处或更多的皮肤。这会给猪带来压力，导致受伤、感染风险增加和体重增加减少。该提案旨在解决猪的攻击行为重组问题。人们对猪用来解决攻击性遭遇的信息收集和决策过程知之甚少。然而，还有大量关于许多其他动物物种的竞争行为的研究。这项工作极大地受益于基于特定信息收集规则的理论模型的应用。已经开发了两类模型，它们在比赛中使用的策略有所不同。在第一类中，称为自我评估，动物纯粹根据自己的战斗能力和耐力，利用内部线索，而不参考对手的战斗能力，做出战斗决定。当战斗消耗了一定（阈值）的能量后，个体就会放弃，阈值较低的对手就是失败者。在第二类模型中，称为相互评估，动物进行自我评估，但也使用有关对手战斗能力的信息。尽管更复杂，但它具有更大的好处，因为动物可以快速退出可能会失败的战斗。猪是否使用自我评估策略或相互评估策略来解决战斗对升级程度有重大影响。通过自我评估，动物总是会战斗到一定程度，而通过相互评估，使用有关对手的信息将使较弱的动物迅速放弃可能会失败的战斗。通过检查一对不熟悉的猪之间的攻击性相互作用并采用合适的统计框架，该提案将确定所使用的评估策略。与人类性格类似，猪在攻击性方面表现出个体差异，有些个体比其他个体更具攻击性。这些差异如何影响战斗结果以及上面详述的评估类型目前尚不清楚。这将通过一种测量攻击性的技术来揭示。此外，通过将经历过重组的猪与没有先前战斗经验的个体进行比较，可以检验战斗经验对于发展相互评估能力的重要性。该项目的一个重要方面是旨在优化猪的评估能力，以最大程度地减少重组时的攻击性水平。我们将研究在仔猪生命早期通过在断奶前允许相邻仔猪混合来进行社会化，是否能让仔猪具备必要的技能，以便在以后的攻击性遭遇中进行相互评估。最后，将上述研究成果转化为重组情境。将操纵小组组成以优化个人相互评估的能力。这将有利于以最少的战斗形成等级制度。实现这一目标并将这些知识转化为工业有可能改善绝大多数商业化生产的生猪的福利。

项目成果

Aggression as an applied welfare problem studied through a game theoretical approach

通过博弈论方法研究攻击行为作为应用福利问题

• 发表时间: 2016
• 作者: Camerlink I

Freedom to express agonistic behaviour can reduce escalated aggression between pigs

自由表达竞争行为可以减少猪之间不断升级的攻击行为

• 发表时间: 2015
• 作者: Camerlink I

Aggressiveness as a component of fighting ability in pigs using a game-theoretical framework

• DOI: 10.1016/j.anbehav.2015.07.032
• 发表时间: 2015-10-01
• 期刊: ANIMAL BEHAVIOUR
• 影响因子: 2.5
• 作者: Camerlink, Irene;Turner, Simon P.;Arnott, Gareth
• 通讯作者: Arnott, Gareth

Intensity of aggression in pigs depends on their age and experience at testing

猪的攻击性强度取决于它们的年龄和测试经验

• 发表时间: 2017
• 作者: Camerlink I

Bridging Research Disciplines to Advance Animal Welfare Science: A Practical Guide

桥接研究学科以推进动物福利科学：实用指南

• 发表时间: 2022
• 作者: Arnott G