title: Effects of extruded corn or grain sorghum on intake, digestibility, weight gain, and carcasses of finishing steers.
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 x 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 x 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.
authors.affiliation: Department of Animal Science, University of Wyoming, Laramie 82071-3684, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Gaebe
authors.forename: D W
authors.initials: DW
authors.lastname: Sanson
authors.forename: I G
authors.initials: IG
authors.lastname: Rush
authors.forename: M L
authors.initials: ML
authors.lastname: Riley
authors.forename: D L
authors.initials: DL
authors.lastname: Hixon
authors.forename: S I
authors.initials: SI
authors.lastname: Paisley
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D004063:Digestion; D004435:Eating; D002523:Edible Grain; D004734:Energy Metabolism; D005511:Food Handling; D008297:Male; D008460:Meat / Q000592:standards; D011897:Random Allocation; D013213:Starch / Q000378:metabolism; D015430:Weight Gain; D003313:Zea mays
chemical_list: D013213:Starch