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Ruminant production efficiency is affected by the voluntary intake of forages and forage quality. Increasing foraging activity increases energy requirements of animals. Frame size and physiological status also influence energy requirements. Forage quality changes with daily and seasonal fluctuations in temperature and light intensity. Production efficiency of grass-finished cattle may be influenced by these factors. Previous studies show that high quality grass-finished beef can be grown on Hawaii pastures. However, the nutritional quality of consumed forages, such as C4 grasses, has not been evaluated as it pertains to grass-finished beef production. There is a need to identify factors that influence the efficiency of grass-finished beef production A two-year study was conducted on 24 grass-finished cattle at the University of Hawaii, Mealani Agricultural Experiment Station. Animal behavior, BCT (body core temperature), weather variables, and forage quality were assessed during three daily periods (am, noon, pm) over three seasons. Cattle grazing activity was highest during the morning and evening periods compared to the midday for all seasons. Cattle spent the least amount of time laying down; a time when their BCT was highest. Standing and chewing and standing activity were higher during the midday in all seasons but highest in summer. Forage quality varied seasonally and was highest in summer than in fall. Diurnal differences were observed in the carbohydrate values which were highest in the evening through all seasons. Average Daily Gain (ADG) was not significantly greater between the 2012 cohort (0.86 kg/d) and 2013 cohort (0.84 kg/d). All animals were slaughtered at an average of 20 months and a live body weight of 531 kg. Eighty-percent of carcasses graded choice or better. Results from this study provide insight into the influence of forage quality and BCT on grazing behavior and production efficiency and may lead to improved management practices for grass-finished cattle.