Abstract In high grain diets, effects of roughage type or source may depend on diet (adaptation vs. finishing) and grain type fed. In four feedlot trials, alfalfa hay (AH) and alfalfa silage (AS) were compared as roughage types during grain adaptation and finishing phases of production. Roughage types were compared in dry whole corn (DWC), dry rolled corn (DRC), whole high moisture corn (WHMC), and ground high moisture corn (GHMC) diets. Common diets were fed during periods in which direct comparisons of alfalfa or corn types were not made. In adaptation trials, a roughage by corn type interaction ( P < 0.10) was observed for intake when dry corn was fed; steers fed AS with DWC ate more (10.0 kg) than steers fed AS with DRC (9.5 kg), while steers fed AH had similar intakes when fed with DRC (9.7 kg) or DWC (9.6 kg). When high moisture corn diets were fed, greater intakes ( P < 0.05) and gains ( P < 0.10) were observed for steers fed AS than for steers fed AH. Effects of roughage fed in the adaptation period were not carried over into the finishing period, in which high energy diets were fed. In finishing phase trials, effects of roughage type were not observed in steer performance or carcass traits. The data suggest that differences in effects of roughage types are observed only in adaptation diets. Observed performance differences are primarily attributed to differences in quality and/or fiber content between AH and AS.