The Proportion of the Ungrazed Area of the Pasture (PUP) Determines When Forage Intake and Diet Quality Decline in Grazing Systems

Grazing management has to deal with the spatial and temporal heterogeneity of pastures. In this context it is desirable to have a grazing management strategy that can be applied in a wide range of pasture conditions to control daily forage intake, diet quality and thus, animal performance. Sward height has been extensively studied and has been found not to be universally applicable to control the animal response as its relationship with intake changes with sward structure (Prache and Peyraud, 2001; Sollenberger and Burns, 2001) . Selective grazing is a universal phenomenon where, independently of pasture condition, cattle prefer the more nutritious and easily ingested top stratum of the pasture before consuming the deeper strata that impose a lower diet quality and greater restrictions on selective grazing. This study tested the hypothesis that forage intake and diet quality significantly decreases when the top selected stratum is removed across the entire area of the pasture (i.e. the proportion of pasture ungrazed)