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

奶牛在妊娠晚期和哺乳早期受到各种压力，包括与饲养和管理有关的压力，可能会导致奶牛及其后代的健康、生产性能和福利下降。本项目的总体目标是评估和评估妊娠晚期和哺乳早期应激源对奶牛的交互作用和相加效应。具体目标是：1)确定奶牛养殖场中与住房、环境、饲养和管理相关的压力源对妊娠晚期和哺乳期早期奶牛的流行率；2)将这些压力源与产后奶牛的健康和生产性能(即发病率、产奶量、繁殖性能)和新生小牛(即健康、免疫力)联系起来；3)确定这些压力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已验证的压力标记物相关联，验证最高眼温作为过渡奶牛压力的新衡量标准。将进行一项观察性研究，确定潜在应激源(包括温度、放牧密度、分组、重组、饮食变化、疾病)对奶牛及其后代的健康和生产性能的影响，特别是它们的相加效应。为了解决次要目标，将建立粪便皮质醇数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养殖场在妊娠晚期和哺乳期早期饲养和管理奶牛的最佳管理实践，以改善奶牛的健康、生产性能和福利，从而使加拿大生产商保持盈利，并提高消费者信心。

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.