Effect of housing- and management-related stressors in late gestation and early lactation on the health, welfare, and performance of dairy cattle

妊娠后期和泌乳早期奶牛的各种压力来源（包括住房和管理）可能导致奶牛及其后代的健康、生产性能和福利状况不佳。本项目的总体目标是评估和评价妊娠后期和泌乳早期应激源对奶牛的相互作用和加性效应。具体目标将是：1)确定奶牛养殖场妊娠晚期和泌乳早期奶牛的住房、环境、喂养和管理相关压力源的普遍性；2)将这些应激源与产后奶牛（即疾病发病率、产奶量、繁殖性能）和新生牛犊（即健康、免疫）的健康和性能联系起来；3)确定这些应激源如何相互作用和复合以影响这些结果。第二个目标是通过将最高眼温与其他有效的压力标记相关联，验证最高眼温作为过渡期奶牛压力的一种新测量方法。将进行一项观察性研究，确定潜在压力因素（包括高温、放养密度、分组、重新分组、饮食变化、疾病）的影响，特别是它们对奶牛及其后代的健康和生产性能的叠加效应。为了解决次要目标，将建立粪便皮质醇值和最高眼温记录之间的一致性。这些信息将有助于确定奶牛场妊娠晚期和泌乳早期奶牛的住房和管理的最佳管理做法，以改善牛的健康、性能和福利，从而使加拿大生产商保持盈利，并增强消费者的信心。

Various sources of stress, both housing and management related, for dairy cows in late gestation and early lactation may lead to poor health, performance, and welfare for both cows and their offspring. The overall objective of this project is to assess and evaluate the interactive and additive effects of late-gestation and early-lactation stressors on dairy cows. The specific objectives will be to: 1) identify the prevalence of housing, environmental, feeding and management related stressors on late-gestation and early-lactation cows in dairy farms; 2) associate these stressors with the health and performance of postpartum cows (i.e., disease incidence, milk production, reproductive performance) and neonatal calves (i.e., health, immunity), and 3) determine how these stressors interact and compound to affect these outcomes. A secondary objective is to validate maximum eye temperature as a novel measure of stress in transition cows by correlating that with other validated markers of stress. An observational study will occur in which the effect of potential stressors (including heat, stocking density, grouping, regrouping, dietary changes, disease) will be determined, particularly their additive effect, on the health and performance of cows and their offspring. To address the secondary objective, agreement between the fecal cortisol values and maximum eye temperature recording will be established. This information will be useful for identifying best management practices for housing and management of cows in late gestation and early lactation in dairy farms to improve cattle health, performance, and welfare, thus allowing Canadian producers to remain profitable and also increasing consumer confidence.