Holtshausen, L., Beauchemin, K. A., Schwartzkopf-Genswein, K. S., González, L. A., McAllister, T. A. and Gibb, D. J. 2011. Performance, feeding behaviour and rumen pH profile of beef cattle fed corn silage in combination with barley grain, corn or wheat distillers' grain or wheat middlings. Can. J. Anim. Sci. 91: 703-710. This study compared growth performance, feeding behaviour and ruminal pH profile of growing beef heifers fed a total mixed ration (TMR) containing corn silage and either [400 g kg^-1 dry matter (DM)] barley grain (CTL), corn dried distillers' grain with solubles (CDDGS), wheat dried distillers' grain with solubles (WDDGS) or wheat middlings (WM). Eighty beef heifers (16 ruminally cannulated; 301±34 kg) were blocked by weight and randomly assigned to eight feedlot pens for a 70-d backgrounding study. Pens were randomly assigned to one of four dietary treatments and equipped with the GrowSafe feed intake system for determining individual feed intake and monitoring feeding behaviour. Dry matter intake (DMI) was lower (P<0.01) and average daily gain (ADG) tended to be lower for CTL (P=0.06) heifers as compared with heifers on other treatments. Feed conversion efficiency (i.e., gain to feed ratio; P=0.41) and feeding behaviour and ruminal pH profile measurements (P>0.05) did not differ among treatments. This study illustrates that barley grain can be replaced by corn dried distillers' grain, wheat dried distillers' grain or wheat middlings in diets fed to growing beef cattle without compromising feed conversion efficiency, adversely affecting feeding behaviour (e.g., decreased meal frequency and duration) or increasing the incidence of ruminal acidosis.