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

作为决定牛对某种疾病的易感性或复原力的关键因素之一，最近受到关注的一个因素是动物的性情。牛的性情被定义为决定动物如何应对任何特定情况的一系列行为特征，有两种方式可以调节牛对健康挑战的生理和生理反应。首先，脾气暴躁的牛更易受伤（如跛行），并可能影响获得环境和社会资源（如不良喂养方式）。其次，某些气质模式与较高的应激激素（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特征来预测个体与治疗失败和负面健康结果的关联。肉牛产业在很大程度上依赖于临床体征的目视观察来评价牛群健康状况，因此在个体水平上，牛气质研究对疾病发病机制的预测和预防价值证据有限。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，每年给肉牛产业造成重大损失；这发生在公众对动物福利和抗菌素使用的负面看法中。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的一个风险因素的作用，将使我们能够更好地识别和管理患病风险较高的牛。本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，从而相应地管理高风险的牛。为了验证这一假设，我们将：1)开发和评估坡道侧测试在饲养场表征动物气质的有效性；2)确定不同气质剖面与牛健康福利多项指标之间的关系；3)评估替代的饲养场健康计划，这些计划包括针对特定牛的脾气量身定制的不同健康协议，以减少抗菌剂的使用、牛的发病率和死亡率。拟议研究项目的成果是对牛的性情在饲养场应对能力中的作用的机制理解，并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.