REVIEW: The Interaction of Diurnal Grazing Pattern, Ruminal Metabolism, Nutrient Supply, and Management in Cattle

Abstract

<h2>ABSTRACT</h2> Daily herbage intake depends on factors governing the initiation and cessation of successive grazing bouts. Ruminal fill is one such factor, regulating grazing bout-eating behavior. Under grazing conditions, nutrient supply varies among grazing bouts, not only in amount, but also in balance. Also, there is evidence suggesting differential energy expenditures in herbage harvesting and ingestive mastication among grazing bouts. The animal internal state plays an important role in shaping grazing pattern, although demands of ruminal microflora may be at times more important. It may well be that perception of ruminal conditions most likely dominates the short-term intake rate during a complete grazing bout, whereas on a larger spatiotemporal scale, the animal may operate within a framework of daily level of energy demand. Simultaneously, cattle might be dealing with pasture progressive defoliation as the grazing event progresses. This leads to selective behaviors and herbage intake rate reductions. From this work emerges that integrating different ingestive and digestive behaviors across foraging spatio-temporal scales would provide greater comprehension of factors driving the diurnal grazing patterns of cattle, helping in the design of better grazing methods.