Factors influencing characteristics of steam-flaked corn and utilization by finishing cattle.

Three experiments were conducted to identify factors influencing steam-flaked corn (SFC) characteristics and feeding value. In Exp. 1, corn samples (n = 108) were tempered for 2 h using 6, 10, or 14% moisture containing 0 or 0.67 mL of surfactant/L. Samples were steamed for 20 or 40 min and flaked to 360, 335, or 310 g/L. Treatments were arranged in a 3 x 2 x 2 x 3 factorial. No interactions existed in Exp. 1. Increasing tempering moisture linearly (P < 0.001) increased corn moisture after tempering, steaming, and flaking; however, SFC moisture was not increased (quadratic; P < 0.001) greatly by applying more than 10% water during tempering. The surfactant, steam time, and flake density had no effect (P = 0.16 to 0.93) on corn moisture after tempering, steaming, or flaking, but adding a surfactant during tempering decreased (P = 0.05) moisture loss after flaking. Starch availability was unaffected (P = 0.31 to 0.84) by tempering moisture concentration, tempering with a surfactant, or steam time but was increased (linear; P < 0.01) by decreasing flake density. Flake durability was increased by increasing tempering moisture (linear; P < 0.001), tempering with a surfactant (P = 0.04), increasing steam time (P < 0.001), and decreasing flake density (linear; P = 0.02). In Exp. 2, 89 heifers (initial BW = 350 kg) were fed 75% SFC-based diets for 108 d to determine the effects of SFC particle size on performance and carcass traits. Treatments were SFC that was mixed for 0 (4,667 microm) or 15 min (3,330 microm) before addition of other ingredients. Heifers fed 3,330-microm SFC tended (P = 0.13) to eat less DM, but ADG and G:F did not differ (P = 0.58 to 0.65) between treatments. Carcass traits did not differ, except that heifers fed 3,330-microm SFC had less (P = 0.008) KPH. In Exp. 3, 96 heifers (initial BW = 389 kg) were fed for 82 d diets containing 73% SFC that was either 18 or 36% moisture. Heifers fed 36% moisture SFC ate less DM (P = 0.02) and gained slower (P = 0.05) than heifers fed 18% moisture SFC, but G:F did not differ (P = 0.93) with SFC moisture. Heifers fed 36% moisture SFC were fatter at the 12th rib (P = 0.009), but all other carcass traits did not differ. Methods that increase moisture of SFC improved durability, but extreme moisture levels negatively affected cattle performance. Flake particle size did not affect cattle performance. Flake density is the major factor affecting starch availability in SFC.