The objective of this study was evaluated the performance of beef cattle fed with whole grain diet and different levels of roughage during the adaptation period. The animals were kept in the feedlot in group pens (6 pens/treatment) for 120-d, with 21-d adaptation period and 99-d finishing period. Seventy 2 Nellore bulls were used in a randomized complete block design with 3 treatments and 6 replicates. All animals were fed with 85% of whole grain and 15% of pelleted feed (soybean, minerals and the additive, virginiamycin)(WG), and the treatments were defined by level of roughage (R) includes in diet, as follow: 0%R (animals fed with 100%WG during adaptation and finishing period); 15%R (animals fed with 85%WG:15%R during adaptation and 100% WG during finishing period) and 5% R (animals fed with 85%WG:15% R during adaptation and 95% WG:5% R during finishing period).In this study was evaluated the dry matter intake (DMI), average daily gain (ADG) and gain:feed (G:F). There were no differences (P > 0.05) for those variables between treatments. All animals showed the same performance and G:F, independent of roughage level in the diet. The roughage may be a problem in finishing cattle diet due to its management and storage. Therefore, animals fed without a roughage source may show the same performance when the roughage is added in the high grain diet. Table 1. Performance of beef cattle fed with different levels of roughage in high whole grain diet

Variable	Treatment			SEM	P-value
0% R	15% R	5% R
DMI (kg/d)	7.658	7.525	7.116	0.219	0.238
IBW (kg)	316	315	316	0.765	0.658
FBW (kg)	485	479	477	7.964	0.766
ADG (kg/d)	1.412	1.365	1.348	0.064	0.773
G:F	0.187	0.182	0.190	0.007	0.748