Increased dietary rumen degradable protein from soybean meal improved growth performance but increased liver abscess severity in finishing beef steers

Objective

Our objective was to determine whether partial or complete replacement of dried distillers grains plus solubles (DDGS) with solvent-extracted soybean meal (SBM) in diets based on high-moisture corn affected growth performance, sera urea nitrogen (SUN) concentrations, and carcass traits in finishing steers.

Materials and Methods

Beef steers (n = 189; initial shrunk BW = 381 ± 37.1 kg) were used in a 139-d experiment. Treatments were DDGS fed at 20% DM (DDGS), SBM replacing 50% of DDGS (SBM50), and SBM replacing 100% of DDGS (SBM100). Steers were allotted to 1 of 24 pens (8 pens per treatment). Sera was harvested on d 77, 105, and 139 for determination of SUN. Linear and quadratic effects were evaluated using orthogonal polynomials with SUN analyzed as repeated measures.

Results and Discussion

Feeding SBM increased final BW (linear). Treatment affected ADG (quadratic) and G:F. Treatment tended to affect carcass-adjusted G:F (quadratic), and SBM increased dietary NE (linear). The SBM100 had greater rib-eye area (linear) but decreased DP (linear). Additional SBM altered liver scores with SBM100 having more severe abscesses. Day and treatment affected SUN, increasing over time, and steers fed SBM100 had greater SUN concentrations than those fed DDGS.

Implications and Applications

Replacement of DDGS with SBM increased retained protein and rib-eye area, tended to decrease DP, and tended to quadratically improve G:F, with increased liver abscess severity.