EFFECTS OF BARLEY VARIETY AND PROCESSING METHODS ON FEEDLOT STEER PERFORMANCE AND CARCASS CHARACTERISTICS

An experiment was conducted to evaluate ammoniation and temper process ing of two barley varieties of diverse types on feedlot cattle perform ance and diet digestibility. Steptoe (feed variety) and Klages (maltin g variety) barleys were processed as dry-rolled (DR); tempered and rol led (TR); tempered, ammoniated, and rolled (AR); and tempered, ammonia ted, and fed whole (AW). Crossbred steers (n = 240, initial weight 266 kg) were blocked by weight and randomly assigned to one of eight trea tments in a 2 x 4 factorial arrangement. Diets contained 30% barley (D M basis) for the growing phase and 85% (DM basis) for the finishing ph ase. Growing phase ADG and gain to feed (G/F) were less (P < .05) for AW than for DR, TR, and AR. Average daily gain was less (P < .05) for AW than for TR and AR in the finishing phase. There were no difference s (P > .05) in ADG or G/F between DR, TR, and AR during growing or fin ishing phases. Gain to feed was greater (P < .05) for TR and AR than f or AW but not for DR for the total trial. Hot carcass weight, longissi mus muscle area, and kidney-pelvic-heart fat were greater (P < .05) fo r TR and AR than for AW. Total finishing diet ADF digestibility was gr eater (P < .05) for Steptoe than for Klages (40.5 vs 31.4%, respective ly). The DR treatment had the lowest ADF digestibility, whereas AR had the greatest (P < .05). Results suggest that there were no difference s in feedlot steer performance due to barley varieties of the same bul k density and that barley grain must be mechanically processed for opt imal performance response rather than ammoniated and fed as whole grai n.