Grazing ruminants consume their food in discrete grazing events. The frequency and distribution of these events depend on the current physiological state of the animal and its environment. Within a small spatio-temporal scale, foraging decisions such as when to begin, which frequency, and how to distribute the grazing events may determine how cattle allocate time to meet their nutritional needs. The longest and most intense grazing events occur normally at dusk; this intake pattern serves to maximize daily energy intake, provide a steady release of nutrients, and maintain satiety over the night. Although ruminants may have a high motivation to seek food at dawn, this grazing event normally is of lesser intensity and duration than the dusk grazing event. Because of the timing of these grazing events, ruminants seem to be crepuscular animals, and light provides an environmental cue as to when to seek food. Certainly, the preference for twilight grazing plays a role in shaping the daily grazing pattern, yet it remains to be explained if this preference also reflects temporal variation in the underlying physiology. On the other hand, modern husbandry could not have eliminated any evolved anti-predator strategy legated by their ancestors. Voluntary feed intake ultimately abuts on animal psychology. Clearly, there are major gaps in our knowledge because there are virtually no published data relating the last question to domestic ruminants.
Gregorini, P., Tamminga, S., & Gunther, S. A. (2006). Review: Behavior and daily grazing patterns of cattle. Professional Animal Scientist, 22(3), 201-209. https://doi.org/10.15232/S1080-7446(15)31095-0