Influence of replacing barley grain with corn-based dried distillers grains with solubles on production and carcass characteristics of growing and finishing beef steers

Abstract

A series of in vivo experiments was conducted for the effects of supplementing corn-based dried distillers grains with solubles (DDGS) to a barley ration for growing and finishing beef steers on growth performance, digestibility, ruminal fermentation and carcass characteristics. Forty-five predominantly British-based crossbred steers (initial body weight (BW) = 257 ± 16 kg) were used in these trials. Steers were housed in groups of 5 in shaded pens, and they received one out of three treatment diets: control without DDGS (C), low inclusion level of DDGS (LD) and high inclusion level of DDGS (HD). The concentrate of the C diet consisted of only dry rolled barley, whereas the LD and the HD diets contained both dry rolled barley and DDGS. While the growing diet contained 105 and 175 g DDGS/kg diet dry matter (DM) to the LD and HD diets, the finishing diet comprised 114 and 183 g DDGS/kg diet DM to the LD and HD diets, respectively. In a completely randomized design, the growing and the finishing trials lasted for 84 and 112 d, respectively, and BW change, DM intake, average daily gain (ADG), gain to feed ratio (G:F) and carcass characteristics were measured. Right after completion of the performance trials, a digestibility trial was performed to test the C and HD diets used in the growing trial to assess digestibility and ruminal fermentation in a replicated 2 × 2 Latin square design using four beef cows. Initial and final BW did not differ among treatments in the growing and the finishing trials (P>0.55). However, growing steers fed the HD diet gained the largest BW followed by the LD and the C diets (P=0.05). Intake of DM decreased as more DDGS were included in the growing diets (P<0.01). Thus, ADG (P=0.05) and G:F (P=0.02) were improved by including DDGS in the diets regardless of level of DDGS. Supplementing DDGS to the finishing diets decreased DM intake (P=0.01) and tended (P=0.14) to increase G:F, although there were no differences between the LD and the HD diets. Supplementation of DDGS tended to increase marbling score (P=0.11) and yield grade (P=0.06), but tended to decrease ribeye area (P=0.09). In addition, feeding the HD diet increased backfat thickness compared with the C and the LD diets. While DM and acid detergent fiber digestibilities did not differ (P>0.48), neutral detergent fiber (aNDF) digestibility tended (P=0.14) to increase with feeding the HD diet. Ruminal pH numerically increased with the HD diet, but it failed to have a significant effect (P=0.33). Supplementing DDGS in a barley ration to growing and finishing steers resulted in no adverse effects on performance, digestion, ruminal fermentation and carcass characteristics, although DM intake was reduced at relatively lower inclusion rates of DDGS compared with those typically used in other studies. The LD and HD diets improved ADG and G:F of growing steers, whereas both diets resulted in similar responses on ADG and G:F of finishing steers compared to the C diet. The positive responses of growing steers are likely due to increases in ruminal pH and aNDF digestion. With increasing availability and economic feasibility, DDGS can be effectively supplemented to barley-based beef diets up to 183 g/kg diet DM.