Abstract: Crossbreed steer calves (n=216; 267?6.8 kg) were used in a growth-performance trial to determine the influence of level and method of supplementation on the utilization of supplemental fat (tallow fatty acids) in high-energy diets for feedlot cattle. Three methods of fat supplementation (fat added directly to the grain, fat added directly to the hay, and fat added as the last step in the batch mixing) were compare at each 3 levels of supplementation (3, 6 and 9% fat). Adding fat directly to the grain, or as the last step in batch mixing had similar (P > 0.10) effects on growth performance. The addition of fat directly to the hay depressed DMI and ADG at the 3 and 9% levels of fat supplementation (fat level by method of supplementation interaction, P < 0.05). Method of fat supplementation did not affect (P >0.10) dietary NE. Increasing the level of fat supplementation decreased (linear effect, P < 0.01) ADG, DMI, feed efficiency, and dietary NE. Observed/expected dietary NEm was 1.03 with 3% supplemental fat and declined to 0.90 with 9% of fat supplementation. We conclude that the feeding value of fat is proportional to total fat intake. When total dietary fat intake is less than 6% the NE value of fat is consistent with tabular values. At greater dietary fat concentrations, energy intake, ADG, and the NE value of fat will decrease. When the proportion of fat added directly forage is greater than 20% of the fat-forage blend energy intake, and hence, daily weight gain may be depressed. However, there are no associative effects of method of supplementations on the dietary NE, even when the level of fat supplementation exceeds 2 g Kg BW-1.