ABSTRACT:We conducted two trials to evaluate the effects of extruding vs dry-rolling either corn or grain sorghum on intake, digestibility, and performance of finishing steers. In Trial 1, 92 crossbred steers (average BW 413 kg) were used in a 2 × 2 factorial design. Diets contained either dry-rolled corn (RC), extruded corn (EC), dry-rolled grain sorghum (RGS), or extruded grain sorghum (EGS). Diets were fed for 110 d and contained 78.6% of the respective grain, 9% alfalfa pellets, 8.2% molasses, and 4.2% protein-mineral supplement. Daily gain was highest ( P < .049) for steers fed RC, and the ADG of steers fed RGS was higher than that of steers fed extruded diets; there was no difference in ADG between steers fed EC and those fed EGS. Steers fed dry-rolled diets consumed more DM ( P = .001) than steers fed extruded diets. Feed efficiency was not affected ( P = .18) by processing method, but steers fed corn utilized the diets more efficiently ( P = .006) than steers fed grain sorghum. Except for carcass weight, carcass data were not affected by grain type ( P > .20).Dressing percentage, quality grade, and longissimus muscle area were lower ( P < .09) in steers that received extruded grain than in those that received dry-rolled grain. In Trial 2, five ruminally cannulated crossbred steers (average BW 518 kg) were used in a 4 × 4 + 1 Latin square design to evaluate the ruminal and total tract digestion characteristics of the diets used in Trial 1. Type of grain had no effect ( P > .16) on intake, total tract digestibility, or ruminal pH. Extruding corn or grain sorghum decreased intake ( P < .001) but increased ( P < .074) DM and starch digestibility compared with dry rolling; steers fed extruded diets had lower ( P < .032) ADF and NDF digestibilities. Ruminal in situ DM and starch disappearance were higher ( P < .03) and ruminal pH was lower ( P < .052) in steers fed extruded grains than in those fed dry-rolled grains. Data from this study indicate that extruded corn and extruded grain sorghum are highly degradable feeds; however, decreased DM intake and lower ruminal pH levels resulted in lower performance.
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