Effects Of Steam-Flaked Corn Density And Roughage Concentration On In Vitro Fermentation, Performance, Carcass Quality, And Acid-Base Balance Of Finishing Beef Cattle, And Particle Distribution Of Corn Steam Flaked To Varying Densities

In Exp. 1, 128 beef steers were used in a 2 x 2 factorial to evaluate bulk densities of steam-flaked corn (SFC; 335 or 386 g/L) and roughage concentration (6 or 10% ground alfalfa hay in the dietary DM) on finishing performance and carcass characteristics. In Exp. 2 effects of bulk density of SFC (283, 335, or 386 g/L) and roughage concentration (6 or 10% ground alfalfa hay) on in vitro DM disappearance (IVDMD) and pH decline were evaluated. In Exp. 3 the effects of bulk density of steam-flaked corn and roughage concentration (335g/L SFC with 6% ground alfalfa hay or 386 g/L SFC with 10% alfalfa hay) on performance, rate of intake, and acid-base balance were evaluated in 24 Holstein steers in a completely random design. In Exp. 4, particle size distribution and associated CP, P, NDF, and starch concentrations in SFC processed to bulk densities of 283, 335, and 386 g/L were evaluated in a completely random design. Overall findings indicated that cattle fed 335 g/L SFC were more efficient than those fed 386 g/L, and that feeding 6% ground alfalfa as the roughage source tended improve efficiency compared with 10% alfalfa hay. In Exp. 2, in a reduced-strength buffer in vitro fermentation system, IVDMD was less as bulk density increased, whereas pH increased with increasing bulk density at 6 and 12 h, but in a regular strength-buffer system, bulk density of SFC and roughage concentration did not affect IVDMD at 6, 12, 18, or 24 h. In addition, bulk density of SFC and roughage concentration within the ranges fed had little effect on blood acid base balance in Exp. 3; however, the combination of greater bulk density and greater roughage concentration increased rate of feed consumption on d 14. For the range of bulk densities of SFC produced in Exp. 4, nutrients were not lost during steam flaking; however, some nutrients accumulated in finer particles created during the steam flaking process. If smaller particles are disproportionately sampled, flaked corn would seem to differ in composition from the intact grain.