DIURNAL EATING PATTERN AND PERFORMANCE OF CATTLE STRIP GRAZED WITH AFTERNOON HERBAGE ALLOCATION OR CONTINUOUSLY VARIABLE STOCKED P. Gregorini, M. Eirin, L. Agnelli, R. Refi, O. Ansin, C. Masino, M. H. Wade, K. Soder, and S. A. Gunter 1 Abstract The objective of this work were to analyze grazing behavior and performance of beef heifers strip grazing with herbage allocation at 1500 each afternoon (AHA) or continuously variable stocked (CS). Measurements were eating, rumination and idling times during daylight hours, and their patterns, as well as bite rate, ADG and change in BCS. The AHA decreased daylight eating time (P < 0.05). Both AHA and CS concentrated eating time in the evening (P < 0.05); however, it was proportionally longer (P  0.05) for AHA. Bite rate was always higher (P < 0.05) for AHA. The ADG and changes in BCS did not differ (P  0.05) between treatments. Alteration of natural grazing pattern was not enough to significantly impact on animal performance. Introduction : Herbage shows a significant variation in diurnal chemical composition (Mayland et al., 2005). Its DM and nonstructural carbohydrate concentration increase over the day, which results in a decrease in NDF concentration (Delagarde et al., 2000) and an increase in digestibility (Gregorini et al 2006a). Because of the diurnal fluctuation of herbage chemical composition when to begin and how to distribute the grazing bouts might be a key decision in determining how cattle allocate eating time to meet their 1 Research Animal Scientist, Pasture Systems and Watershed Management Research Unit (PSWMRU), USDA-ARS, University Park, 16801 PA; Assoc. Professor, Faculty of Agricultural and Forestry Sciences (FCA&F), National University of La Plata (UNLP), La Plata, 1900, Argentina; Assist. Professor, FCA&F, UNLP; Professor, FCA&F, UNLP; Professor, FCA&F, UNLP; Research Assistant, FCA&F, UNLP, Professor, national University of the Center of Buenos Aires Province; Research Animal Scientist, PSWMRU, USDA-ARS; Professor, Division of Agriculture, University of Arkansas. Southwest Research and Extension Center, Hope, AR 71801.