Abstract The objective was to determine if increasing roughage equivalent (RE) from 7% to 12% (17.5 to 20.5% dietary neutral detergent fiber on a DM basis) in the last 28 days of fattening could improve rumen health parameters and decrease the frequency of liver abscesses without compromising productive efficiency or carcass characteristics. Charolais × Angus crossbred steers n = 64; n = 8 pens; initial shrunk body weight (SBW) = 633 kg ± 35.1 kg were allocated to dietary treatment in a completely randomized design. All steers were fed a common 7% dry matter (DM) basis roughage equivalent diet (17.5% neutral detergent fiber NDF DM basis) where the roughage sources were based upon corn silage and hay for the 58 d prior to study initiation. The treatments involved increasing the dietary forage concentration from 7% to 12% for the final 28 days on feed, as follows: 1) No diet change (7R) and 2) 5% (DM basis) roughage equivalent addition to 7R via grass hay during the final 28 DOF to increase the dietary NDF to 20.5% DM basis (12R). Steers were finished on treatment diets for 28 d prior to harvest. No differences (P ≥ 0.19) were observed for any growth performance, efficiency, or carcass trait measures except for marbling scores. Marbling score differed (P = 0.04) between treatments with 12R steers exhibiting 5% greater marbling than 7R steers. A treatment × DOF interaction (P 0.01) was observed for minutes ruminating per day. Daily minutes ruminating was increased (P ≤ 0.05) for 12R on d 1, 2, and 20 and tended to be increased (P ≤ 0.10) for 12R on d 10, 13, 24, and 25. Rumenitis score nor liver abscess prevalence was influenced by dietary treatment. Inclusion of an additional 5% RE to cattle diets during the final 28 DOF can be a management strategy to maintain ruminal health without sacrificing growth performance or carcass quality, but does not appear to reduce incidence of liver abscessation.
Francis et al. (Fri,) studied this question.