344 Impact of Removing 20% Distillers Grains After one-Third or two-Thirds of the Feeding Period on Performance of Finishing Yearlings

Abstract Crossbred, yearling beef steers (n = 210: initial BW = 430 ± 22 kg) were used in a randomized blocked design finishing experiment to evaluate the impact of removing modified distillers grains plus solubles (MDGS) on finishing performance and carcass characteristics. Treatments included feeding 20% MDGS (DM basis) during the entire feeding period (124 d); 20% MDGS until day 79 and then 0% MDGS until the end of the feeding period; or 20% MDGS until day 43 and then 0% MDGS until the end of the feeding period. A total of 21 pens (10 steers/pen) were used with 7 pens/treatment. Cattle were fed a 60:40 blend of high-moisture and dry-rolled corn, with 15% corn silage, 20% MDGS and 5% supplement. Distillers were replaced with the corn blend and urea when removed. Cattle were stepped down to 10% MDGS for 4 days before the complete removal of MDGS. Cattle with MDGS removed on either d 79 or d 43 had reduced (P < 0.05) final BW, DMI, and ADG. Cattle with MDGS removed on d 43 were 5% less efficient (P < 0.05) than cattle fed 20% MDGS throughout the entire feeding period. Cattle fed 20% MDGS throughout the whole feeding had the greatest (P < 0.05) HCW and LM area. There were no differences (P ≥ 0.35) in backfat and marbling scores among treatments, and no differences (P = 0.59) in percent of abscessed livers, although 38% of steers fed 20% MDGS continuously had liver abscesses compared with 46% for steers with MDGS removed on d 43. Based on the results of this study, removing MDGS from finishing diets on either day 43 or day 79 of the feeding period had a negative impact on cattle performance compared with feeding 20% MDGS continuously throughout the entire finishing period.