Irrigated pasture grazing trials were conducted during three grazing seasons (years) to investigate systems for rearing early-breeding replacement beef heifers. Seven- to 8-month-old weaner beef heifers grazing irrigated pasture were supplemented with barley. Supplemental treatments were (1) none, (2) three times per week (MWF), (3) daily (fed weekly-intake limited by salt to be consumed over 7 days) and (4) same amount as (2) and (3) would consume in 4 weeks but hand fed to be consumed in 2 weeks. The third year one treatment was supplemented only during the last 56 days of the grazing trial. Data collected included supplement consumption, weight gains, pasture composition and height as well as “in vitro” digestibility of the forage and the grazing, eating barley, ruminating and idling times for the grazing heifers. Supplementation increased ADG and supplementing for 2 weeks followed by no grain for 2 weeks in general increased ADG more than other supplemental treatments. The heifer grazing, eating supplements and ruminating patterns and the forage data indicate that supplements were consumed at times normally spent in grazing and not in addition to grazing. The results suggest that all phases of management, genetics and nutrition must be considered if rearing replacement heifers for early-breeding is to be successful.