Many early studies laid the foundation for our understanding of the mechanics of chewing, the physiological role of chewing for the cow, and how chewing behavior is affected by dietary characteristics. However, the dairy cow has changed significantly over the past decades, as have the types of diets fed and the production systems used. The plethora of literature published in recent years provides new insights on eating and ruminating activity of dairy cows. Lactating dairy cows spend about 4.5 h/d eating (range: 2.4–8.5 h/d) and 7 h/d ruminating (range: 2.5–10.5 h/d), with a maximum total chewing time of 16 h/d. Chewing time is affected by many factors, most importantly whether access to feed is restricted, intake of neutral detergent fiber from forages, and mean particle size of the diet. Feed restriction and long particles (≥19 mm) have a greater effect on eating time, whereas intake of forage neutral detergent fiber and medium particles (4–19 mm) affects rumination time. It is well entrenched in the literature that promoting chewing increases salivary secretion of dairy cows, which helps reduce the risk of acidosis. However, the net effect of a change in chewing time on rumen buffing is likely rather small; therefore, acidosis prevention strategies need to be broad. Damage to plant tissues during mastication creates sites that provide access to fungi, adhesion of bacteria, and formation of biofilms that progressively degrade carbohydrates. Rumination and eating are the main ways in which feed is reduced in particle size. Contractions of the rumen increase during eating and ruminating activity and help move small particles to the escapable pool and into the omasum. Use of recently developed low-cost sensors that monitor chewing activity of dairy cows in commercial facilities can provide information that is helpful in management decisions, especially when combined with other criteria. Although accuracy and precision can be somewhat variable depending on sensor and conditions of use, relative changes in cow behavior, such as a marked decrease in rumination time of a cow or sustained low rumination time compared with a contemporary group of cows, can be used to help detect estrus, parturition, and some illnesses. This review provides a comprehensive understanding of the dietary, animal, and management factors that affect eating and ruminating behavior in dairy cows and presents an overview of the physiological importance of chewing with emphasis on recent developments and practical implications for feeding and managing the modern housed dairy cow.

许多早期研究为我们理解咀嚼的机理，咀嚼母牛的生理作用以及饮食特性如何影响咀嚼行为奠定了基础。然而，在过去的几十年中，奶牛，饲喂日粮的类型和所使用的生产系统都发生了重大变化。近年来发表的大量文献为奶牛的进食和反刍活动提供了新的见解。泌乳奶牛的进食时间约为4.5 h / d（范围：2.4–8.5 h / d）和反刍7 h / d（范围：2.5–10.5 h / d），最长总咀嚼时间为16 h / d。咀嚼时间受许多因素影响，最重要的是是否限制饲料的获取，从草料中摄取中性洗涤剂纤维以及日粮的平均粒径。饲料限制和长颗粒（≥19 mm）对进食时间有较大影响，而中性牧草洗涤剂纤维和中等颗粒（4–19 mm）的摄入会影响反刍时间。在文献中根深蒂固的是，促进咀嚼可增加奶牛的唾液分泌，从而有助于降低酸中毒的风险。但是，咀嚼时间的变化对瘤胃抛光的净影响可能很小。因此，酸中毒的预防策略需要广泛。咀嚼过程中对植物组织的破坏产生了可以进入真菌，细菌附着以及逐渐降解碳水化合物的生物膜形成的部位。反刍和进食是减少饲料粒度的主要方法。在进食和反刍活动期间，瘤胃的收缩增加，并有助于将小颗粒移到可逃逸的水池中并进入到气味中。使用最近开发的低成本传感器来监视商业设施中奶牛的咀嚼活动可以提供有助于管理决策的信息，尤其是与其他标准结合使用时。尽管精度和精确度可能会因传感器和使用条件的不同而有所不同，但是可以使用奶牛行为的相对变化（例如与当代奶牛相比显着减少的反刍时间或持续的低反刍时间）来进行检测。帮助检测发情，分娩和某些疾病。这篇评论全面了解了饮食，动物，