This study was conducted to determine the effect of dietary tannin on growth performance, rumen fluid characteristics, and apparent total-tract digestibility in growing Holstein-Friesian x Sahiwal bulls fed low and high energy rations. Therefore, feeding concentrates containing 2.47 Mcal/kg ME without additional tannin can still be fed economically to growing cattle without any adverse effect on growth, ruminal fermentation characteristics, and apparent total-tract digestibility.