Crossbred heifers (n = 120; BW = 368 kg, SD = 39 kg) were used to determine effects of dried distillers grains (DDG) and relative contributions of undegradable intake protein (UIP) and fat (ether extract, EE) in DDG on ADG and forage intake (FI). Heifers rotationally grazed six 3.5-ha, smooth bromegrass paddocks (IVDMD = 65.7%, CP = 20.8%, UIP = 2.17%, DM basis). Heifers were blocked by previous ADG and allotted to treatments in a 3 × 3 + 1 factorial design. Factors were source and level of supplementation. Supplements were as follows: 1) DDG (UIP = 15.8%, EE = 9.67%), 2) corn gluten meal (CGM; UIP = 31.6%, EE = 0.83%), or 3) corn oil (OIL; UIP = 0.74%, EE = 19.3%). Amounts of DDG were 750, 1,500, or 2,250 g/d, whereas amounts of CGM and OIL were 375, 750, or 1,125 g/ d. Supplements containing CGM and OIL were fed in amounts that provided UIP and EE, respectively, equivalent to those of the DDG. Contrasts of interest were DDG vs. CGM and DDG vs. OIL. Control heifers were fed 250 g/d of a supplement containing corn bran and molasses (UIP = 0.92%, EE = 1.13%). Heifers were supplemented individually. Treatments were separated by regressing the response variables on grams of nutrient