Supplementing Varying Ratios of Modified Distillers Grains and Corn to Growing Beef Steers

An 84-d growing trial was conducted utilizing 120 crossbred steers (initial BW = 281 kg; SD = 15) in a randomized complete block design (n = 10) to determine the effects of displacing modified distillers grains plus solubles (MDGS) with dry-rolled corn (DRC) for steers consuming forage of differing quality on growing performance. Steers were limit fed 5-d and weighed on 2 consecutive days for beginning and ending BW. The experiment was arranged in a 4 x 3 factorial with ratio of MDGS to DRC as the first factor (100:0, 80:20, 60:40, and 40:60) and forage type as the second factor. The 40:60 ratio was designed to still meet the metabolizable protein (MP) requirements of the animal while displacing as much MDGS with DRC as possible. Forage type consisted of either a high quality (HQ; 70% brome hay and 30% sorghum silage) or 1 of 2 low quality forages consisting of corn residue that was baled through a conventional rake and bale method (CB) or by disengaging the spreader on the combine and baling the tailings immediately (easy bale; EZB). Diets consisted of 40% MDGS:DRC energy supplement, 56% forage, and 4% supplement. Ad libitum feed was individually delivered daily via Calan gates. There was no interaction for MDGS:DRC ratio and forage type on ending BW, ADG, or G:F (P > 0.32). Steers consuming HQ forage had greater ADG (1.31 kg/d) than steers consuming either of the low quality forages which did not differ (0.76 kg and 0.81 kg/d for EZB and CB, respectively). Although HQ steers had increased ADG, DMI for HQ was also greater than for EZB and CB leading to no difference in G:F among treatments (P = 0.92). As MDGS was replaced with DRC, there was a linear decrease in ending BW and ADG (1.03 to 0.88 kg/d; P < 0.01). Similarly, G:F decreased linearly (P = 0.03) as MDGS was replaced with corn due to the decline in ADG and no differences in DMI among treatments. As expected, steers fed a high quality forage had increased performance compared to steers fed low quality forage. Even though all ratios of MDGS:DRC were designed to meet MP requirements, these data would suggest a greater energy value for MDGS compared to DRC, observed in the linear decrease in gain with increasing level of DRC.