Influence of wet distillers grains produced from a novel cellulosic ethanol process utilizing corn kernel fiber on feedlot growth and carcass characteristics of steers

Abstract Text: Changes in ethanol production influence the nutrient profile of distillers grains (DG) produced. One recent example of this is a secondary fermentation process involving cellulosic enzymes, yeast, and heat which partially converts corn kernel fiber into cellulosic ethanol, resulting in a novel wet DG product (C-WDG). The objective of this study was to evaluate the impact of feeding C-WDG or traditional WDG (T-WDG) on finishing cattle growth and carcass characteristics. One hundred sixty-eight crossbred steers (421 ± 23.9 kg) were stratified by source, blocked by weight to pens of 6 steers, and assigned to 1 of 4 dietary treatments fed for 94 d. Diets included a corn-based control with 13% T-WDG (CON), 30% T-WDG (TRAD), 30% C-WDG (CEL), or 18% C-WDG plus 12% condensed corn distillers solubles (CEL+CCDS). Co-products replaced corn on a DM basis. Data were analyzed as a randomized complete block design with pen as the experimental unit (n = 7/treatment). Three comparisons were made: 1) CON vs. TRAD, 2) TRAD vs. CEL, and 3) CEL vs. CEL+CCDS. Data presented are LSMEANS ± pooled SEM. Steers fed TRAD had greater (P ≤ 0.01) ADG (1.75 ± 0.03 kg), G:F (0.166 ± 0.003), and HCW (372 ± 2.1 kg), and tended (P = 0.07) to have larger ribeye areas (REA) compared to steers fed CON (ADG 1.59 kg; G:F 0.149; and HCW 364 kg). Although steers fed CEL had decreased G:F (P = 0.02; 0.154) due to increased DMI (P = 0.01; 10.9 ± 0.11 kg) compared to TRAD−fed steers (10.5 kg), no differences (P ≥ 0.16) in ADG, HCW, or REA were observed among steers fed CEL or TRAD. Steers fed CEL had leaner carcasses (P ≤ 0.03; YG of 2.8 ± 0.07) compared to TRAD−fed steers (YG 3.1). Steers fed CEL+CCDS had lesser (P ≤ 0.04) DMI (10.0 kg) and ADG (1.58 kg) than CEL−fed steers (ADG 1.68), while G:F did not differ (P = 0.50). Subsequently, steers fed CEL+CCDS tended (P = 0.07) to have lesser HCW (362 kg) compared to CEL−fed steers (368 kg), likely because of the greater S contributed by the CCDS. Results from this study reiterate that T-WDG are superior to corn in energy content and establish that C-WDG produced from conversion of corn kernel fiber into cellulosic ethanol maintains significant advantage in cattle performance as a replacement for corn in feedlot diets.

Keywords: cellulosic ethanol, corn fiber, distillers grains