Development of a chute-side test to use feedlot cattle temperament as an indicator of disease resilience

最近在决定牛对疾病的易感性或恢复力的关键因素中，动物的性情是受到关注的因素之一。定义为一组行为特征，决定了动物如何对任何给定的情况做出反应，牛的气质如何调节身体和生理对健康挑战的反应有两种方式。首先，脾气暴躁使牛更容易受伤(例如，跛行)，并可能影响获得环境和社会资源(例如，不良饲养模式)。其次，某些气质模式与压力荷尔蒙(即皮质醇)的基础浓度较高、生长速度较慢和免疫反应较弱有关。拟议的研究计划旨在利用肉牛气质的准确和系统特征来预测个体与治疗失败和负面健康结果的关联。肉牛业严重依赖临床体征的肉眼观察来评估牛群的健康状况，因此，关于牛的气质研究在个体水平上对疾病发病机制的预测和预防价值的证据有限。营养性和呼吸性饲养牛疾病，如瘤胃酸中毒或牛呼吸道疾病(BRD)，每年由于治疗费用、生长性能下降和死亡率而导致肉牛业重大损失；这发生在公众对动物福利和抗菌剂的使用持负面看法的情况下。最近在预防和诊断工具方面的进展对这些疾病的发病率和严重程度几乎没有影响，因此，更好地了解牛的气质作为其发病原因的风险因素的作用将使我们能够更好地识别和管理患病风险更高的牛。这项研究计划的全球假设是，可以在农场测量肉牛的气质，并将其作为疾病易感性的预测指标，从而管理高危牛。为了验证这一假设，我们将：1)开发和评估用于表征饲养场动物气质的降落伞侧测试的有效性；2)确定不同气质特征与牛健康和福利的多个指标之间的关系；以及3)评估替代饲养场健康计划，其中包含针对特定牛气质量身定做的不同健康方案，以减少抗菌剂的使用、牛的发病率和死亡率。拟议研究计划的成果是机械地理解牛的气质对它们在饲养场的处理情况的作用，并利用这些信息制定牛群健康计划，以缓解影响肉牛健康的最突出的健康问题。

One of the factors that has recently gained attention as a key element in determining cattle susceptibility or resilience to a disease is animal temperament. Defined as a set of behavioural traits that determines how an animal responds to any given situation, there are two ways how cattle temperament can modulate the physical and physiological response to health challenges. First, fractious temperaments predispose cattle to a higher risk of injuries (e.g. lameness) and can influence access to environmental and social resources (e.g. undesirable feeding patterns). Second, certain temperament patterns are associated with greater basal concentrations of stress hormones (i.e. cortisol), lower growth rates and a weaker immune response. The proposed research program aims to use the accurate and systematic characterization of beef cattle temperament to predict individual's associations with treatment failures and negative health outcomes. The beef cattle industry heavily relies on the visual observation of clinical signs to evaluate herd health, and so there is limited evidence on the predictive and preventative value the study of cattle temperament has on disease pathogenesis at an individual level. Nutritional and respiratory feedlot cattle diseases, such as rumen acidosis or bovine respiratory disease (BRD), result in significant losses to the beef cattle industry every year due to treatment expenses, reduced growth performance and mortality; this occurs amid a negative public perception of animal welfare and the use of antimicrobials. Recent advances in prevention and diagnostic tools have had little impact on the incidence and severity of these diseases, hence, a better understanding of the role of cattle temperament as a risk factor on its pathogeneses would allow us to better identify and manage cattle at a higher risk of getting sick. The global hypothesis of this research program is that the temperament of beef cattle can be measured on farm and be used as a predictor of disease susceptibility to manage high-risk cattle accordingly. To test this hypothesis, we will: 1) develop and evaluate the efficacy of chute-side tests to characterize animal temperament at the feedlot; 2) determine the relationship between different temperament profiles and multiple indicators of cattle health and welfare; and 3) assess alternative feedlot health programs that incorporate different health protocols tailored to specific cattle temperaments to reduce antimicrobials use, cattle morbidity and mortality. The deliverables of the proposed research program are a mechanistic understanding of the role of cattle temperament on how well they cope at the feedlot, and the use of this information to develop herd health programs that will mitigate the most prominent health issues affecting beef cattle health.