【摘要】 地球自转带来了周期性的明/暗循环，从而导致了地球表面光照时间、温度和能量等外部环境因素的昼夜节律性变化。生物体为适应这些外界环境因素的变化，在漫长的进化过程中逐渐形成一套内源性的自主调控系统，称为生物钟。从简单的单细胞生物到复杂的多细胞生物，生物体内都普遍存在着生物钟系统。反刍动物生物体内同样存在节律性振荡的生物钟系统，该系统通过与外界环境光-暗周期、温度波动等授时因子的协同作用，参与调控反刍动物采食行为、代谢活动、繁殖功能和免疫应答等大量生理功能的节律性变化。然而，目前学界对反刍动物生物钟系统分子机制及其作用的认识相对有限。该文综述了牛、羊、骆驼等反刍动物昼夜节律生物钟的研究进展，解析其调控机制与生物学基础，探讨外界环境如何通过生物钟系统影响其生理与代谢活动的作用机制，旨在为提升反刍动物的生产性能提供新思路。更多还原

【Abstract】 The earth’s rotation gives rise to periodic light-dark cycles, leading to diurnal rhythmic changes in external environmental factors such as photoperiod, temperature, and energy availability. To adapt to these fluctuations, organisms have evolved an endogenous, self-sustained regulatory system known as the circadian clock. This circadian system is widely conserved across species, from unicellular organisms to complex multicellular animals. In ruminants, rhythmic oscillations of the circadian clock synchronize with environmental cues-such as light-dark cycles and temperature variations-to regulate a wide range of physiological functions, including feeding behavior, metabolic activity, reproductive performance, and immune responses. However, the molecular mechanisms underlying the circadian clock system in ruminants remain relatively underexplored. This review summarizes recent advances in our understanding of the circadian rhythms in ruminants such as cattle, sheep, and camels, elucidates the regulatory mechanisms and biological foundations of their circadian systems, and discusses how environmental factors influence physiological and metabolic processes via the circadian clock. These insights may offer novel strategies to improve the productivity and health of ruminant livestock.更多还原