Beliveau, R. M. and McKinnon, J. J. 2008. Effect of graded levels of wheat-based dried distillers' grains with solubles on performance and carcass characteristics of feedlot steers. Can. J. Anim. Sci. 88: 677-684. A trial was conducted to evaluate graded levels of wheat-based dried distillers' grains with solubles (DDGS) on feedlot performance and carcass characteristics of growing and finishing cattle. Two hundred weaned calves (290 +/- 17 kg) were randomly assigned to 1 of 20 pens and fed one of Five DDGS treatments. The barley grain-based control diet (0% DDGS) was formulated to 12% crude protein (CP) and 1.52 and 0.93 Meal kg(-1) net energy maintenance (NEm) and net energy gain (NE,) respectively, during the backgrounding period and 1.90 and 1.26 Meal kg(-1) NEm and NEg respectively, during finishing. Wheat-based DDGS replaced (DM basis) barley grain at levels of 8, 16, 24 and 32% during backgrounding and 6, 12, 18 and 23% during finishing. Over the 85-d backgrounding period, dry matter intake (DMI) (P = 0.02), average daily gain (ADG) (P = 0.04), and ultrasound (US) 1. dorsi gain (P = 0.02) exhibited a cubic response to DDGS inclusion level with theoretical minima at 6.9. 8.1 and 6.9% DDGS, respectively, and theoretical maxima responses at 27.2, 30.8 and 23.9% DDGS, respectively. Feed efficiency exhibited a quadratic response (P = 0.02) to DDGS inclusion level with a theoretical poorest response at 13.1% DDGS. No effect (P > 0.05) of DDGS inclusion level was noted on ADG, DMI or feed efficiency (kg gain:kg feed; FE) during the finishing period. Similarly, carcass traits were not influenced (P > 0.05) by DDGS inclusion level. The results of this study indicate that wheat-based DDGS can serve as an effective replacement for barley grain in cattle diets supplying both energy and protein and that for finishing cattle, wheat-based DDGS has an energy value at least equal to that of barley grain when fed at levels up to 23% of the diet DM.