Supplementation of high-quality grazed forage with high-energy feedstuffs can improve animal performance and enable increased stocking rates. However, the extent of performance improvement and direction of forage utilization response may be dependent upon supplementation level and whether the supplement is a high-starch or highly-digestible-fiber feedstuff. For these reasons, a grazing experiment was conducted to determine the type and level of supplementation with select high-energy feedstuffs that yield optimum animal performance and forage utilization from annual ryegrass (Lolium multiflorum). Twenty 0.81-ha pastures were each grazed by 4 crossbred steers (235 kg ± 15 kg initial BW) between Feb. 6 and May 15, 2014. Cracked corn (CC), pelleted citrus pulp (CP) or pelleted soybean hulls (SH) were fed at rates of 0.25, 0.50 and 0.75% of steer BW daily (2 rate × supplement replicates per treatment, including replicate pastures in which steers received no supplement). Steers were weighed every 28 d following an overnight shrink. Forage mass was measured every 28 d using the destructive harvest/disk meter dual-sampling method. Data were analyzed as a completely randomized design by the PROC GLM procedure of SAS 9.2 using pasture as the experimental unit. There were no supplement type × level interactions (P > 0.05) observed for either ADG or net forage mass change (FMC). Steers receiving CC and SH supplementation had greater (P < 0.05) ADG (1.30 and 1.23 kg/d, respectively), and steers receiving CP tended (P = 0.07) to have greater ADG (1.20 kg/d) than steers receiving no supplement (0.95 kg/d). Steers supplemented at 0.25 and 0.75% BW had greater (P < 0.05) ADG (1.23 and 1.30 kg, respectively) than steers receiving no supplement (0.95 kg/d). Net FMC over the entire grazing season increased (P < 0.05) in pastures grazed by steers receiving CC (+38 kg DM/ha) compared with those grazed by steers receiving SH (−277 kg/ha). There were no differences in net FMC between any of the supplementation types or levels and the unsupplemented control. Patterns of net FMC response indicate relative underutilization of forage by steers receiving CC (i.e., substitution effect of supplementation) compared with steers receiving SH or CP.