198 Effects of Corn Processing and Silage Inclusion Levels in Feedlot Diets on Steer Performance

Abstract

Abstract Feedlot steers (n = 480, initial BW = 389 kg ± 17 kg) were used to test the interaction between corn processing and silage inclusion on the performance and carcass characteristics. Treatments were designed as a 2 × 4 factorial design experiment with factors as 2 corn processing methods (dry-rolled corn, DRC, and steam-flaked corn, SFC) and 4 inclusions of silage (0, 15, 30, 45% of diet DM). Diets also contained 10% MDGS and 5% supplement. Steers were blocked by BW, assigned randomly to pens, and data analyzed using MIXED procedure of SAS with block fixed and pen (n = 48) as the experimental unit. Steers were fed the same days for all treatments (125 d). No significant interactions were observed between corn processing and silage inclusion for performance or carcass characteristics (P > 0.12), therefore, main effects will be presented. As silage inclusion increased, intake (DMI), gain (ADG), and feed efficiency (G:F) changed quadratically (P < 0.03). Gains were greater for cattle fed 15 or 30% silage and lower diets with 0 or 45% silage. Feed efficiency was greatest for steers fed 0% silage (0.168) and decreased to 0.161 and 0.152 as silage inclusion increased to 15 and 30% inclusion. The quadratic response is due to decreased G:F for steers fed 45% silage (0.139). Carcass characteristics responded similar to ADG quadratic (P < 0.01) impacts on fat depth and marbling. Feeding SFC in comparison to DRC led to increased DMI, ADG, G:F, and fat depth (P < 0.04). Gains were greater for cattle fed SFC than cattle fed DRC, which led to increased G:F (SFC = 0.160, DRC = 0.151) across all silage inclusions. Increasing silage inclusion resulted in greater ADG, marbling, and fat depth with 15 and 30% compared with 0 and 45%. Feeding SFC improved performance compared with DRC.