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Both quantity and quality of pasture forage produced generally varies with frequency and intensity of plant defoliation. However, intensity and frequency of defoliation have rarely been evaluated simultaneously. The objective of this study was to quantify forage quality response to simultaneous changes in defoliation treatments over a range of values likely to occur in short-duration graxing systems. Effects of defoliation treatments on forage digestibility (DMD), crude protein content (CPC), crude protein yield, and digestible dry matter yield were evaluated on a perennial ryegrass (Lolium perenne, L.)-subclover (Trgolium subterraneum L.) hill land pasture growing on a Ultic Hapioxeroll soil near Corvallis, Oregon. Treatments consisted of all possible combinations of 4 defoliation intervals (clipped every 7, 21, 35, or 49 days) and 3 stubble heights (High-70, Medium-55, or Low-40 mm of stubble remaining after defoliation) applied during the 1980, 1981, and 1982 growing seasons. Digestible dry matter yield increased with increasing defoliation interval. With the exception of DMD in 1980, both digestibility and CPC of the forage produced decreased linearly as the period between defoliation events Increased. Crude protein content increased linearly as stubble height Increased, while forage digestibility was comparatively insensitive to changes in stubble height. Forage quality was generally adequate on all treatments to meet the needs of most classes of livestock. This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries. The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020