Two trials were completed to evaluate the se of Bt corn hybrids (de- rived from Event Bt11) for growing steers.Trial 1 utilized ?elds of N7333 Bt and N7333 non-Bt post-harvest corn residue to evaluate daily gain and grazing preference.The absence of signicant European corn borer (ECB )pressure resulted in similar grain yields (184 and 182 bu/acre) and residual corn (1.0 and 1.5bu/acre)for the Bt and non-Bt hybrid,re- spectively.Twenty-three acres of Bt and 21 acres of non-Bt corn residue were divided into 3 pastures and stocked with 8 or 9 steers,providing equal stocking rates.Daily gain of 67 steers grazing corn residue for 70 d was similar (avg.0.28 kg/d).Also,16 steers allowed access to either 7 acres of Bt or non-Bt corn residue demonstrated no grazing preference. In Trial 2,128 steers (avg.282 kg)were fed corn silage diets (90% silage and 10% supplement, DM basis)for 101 d.Treatments were arranged as a 2 x 2 factorial:Bt or non-Bt versions of hybrids N7333 or N4242.Dry matter intake was higher (8.61 vs 8.32 kg/d;P <0.05)for steers fed Bt compared with non-Bt hybrids.An interaction (P <0.05)was observed between hybrid genotype and Bt trait for daily gain and feed effciency. Daily gain was higher (1.46 vs 1.36 kg/d;P <0.05)for steers fed N4242 Bt compared with N4242 non-Bt.Daily gain was similar (avg.1.28 kg/d)for steers fed N7333 Bt and non-Bt.Feed effciency was better (P <0.05)for steers fed N7333 non-Bt (6.33)compared with N7333 Bt (6.81).Feed effciency was similar (avg.6.10)for steers fed N4242 Bt and non-Bt.Although an interaction was present,steers fed the N4242 hybrids gained 11%faster (P <0.01)and were 8%more effcient (P < 0.01)than those fed the N7333 hybrids.Presence of the Bt trait in corn hybrids had no consistent effect on performance of growing steers,while hybrid genotype appeared to affect performance.Higher ECB pressure may indirectly influence grazing performance on Bt and non-Bt corn residue.