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

最近作为决定牛对疾病的易感性或恢复力的关键因素而受到关注的因素之一是动物的性情。牛的性情被定义为一组决定动物如何应对任何特定情况的行为特征，牛的性情可以通过两种方式调节对健康挑战的身体和生理反应。首先，暴躁的性情使牛容易受到更高的伤害风险（例如跛行），并可能影响对环境和社会资源的获取（例如不良的喂养模式）。第二，某些气质模式与更高的压力激素（即皮质醇）基础浓度，较低的生长速度和较弱的免疫反应有关。拟议的研究计划旨在使用肉牛气质的准确和系统的表征来预测个体与治疗失败和负面健康结果的关联。 肉牛产业严重依赖于临床体征的视觉观察来评估牛群健康，因此牛气质研究对个体水平疾病发病机制的预测和预防价值的证据有限。饲养场牛的营养和呼吸系统疾病，如瘤胃酸中毒或牛呼吸系统疾病（BRD），由于治疗费用、生长性能下降和死亡率降低，每年都会给肉牛业造成重大损失;这是在公众对动物福利和使用抗菌剂的负面看法中发生的。预防和诊断工具的最新进展对这些疾病的发病率和严重程度几乎没有影响，因此，更好地了解牛的性情作为其发病机制的风险因素的作用，将使我们能够更好地识别和管理患病风险较高的牛。 该研究计划的总体假设是，肉牛的气质可以在农场测量，并用作疾病易感性的预测因子，以相应地管理高风险牛。为了验证这一假设，我们将：1）开发和评估槽侧测试的有效性，以表征饲养场的动物气质; 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;和3）评估替代的饲养场健康计划，该计划结合了针对特定牛性情定制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。拟议的研究计划的可交付成果是对牛的性情在饲养场科普能力方面的作用的机械理解，以及利用这些信息制定牛群健康计划，以减轻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.