Substitution of modified distillers grains with soybean meal with or without soyhulls had negligible effects on growth performance, efficiency, and carcass traits in yearling beef steers

Abstract

Objective

The objective of this study was to evaluate animal performance, carcass traits, and dietary net energy utilization in finishing beef steers when soybean meal (SBM) with or without soybean hulls (SBH) replaced modified distillers plus solubles (MDGS).

Materials and Methods

Predominately Angus steers (n = 240; initial shrunk BW = 435 ± 23.2 kg) were allotted to 1 of 24 pens. Steers were blocked by location within the feedlot and randomly assigned to 3 treatments: MDGS fed at 15% diet DM (MDGS) replaced by either soybean meal and corn (9 and 6% of DM, respectively; SBM), or soybean meal and soyhull pellets (9% and 6% of DM, respectively; SBM-SBH). Growth performance was calculated on a carcass-adjusted basis (hot carcass weight/0.625). Data were analyzed as a randomized complete block design with random effect of block and fixed effect of treatment; pen was the experimental unit. Orthogonal contrasts were used to determine the effects of protein source (MDGS vs. SBM and SBM-SBH) or starch compared with NDF (SBM vs. MDGS and SBM-SBH). Steers were fed for 118 d until shipped for slaughter at a commercial abattoir where carcass data and liver abscess scores were collected.

Results and Discussion

No differences among treatments (P ≥ 0.11) were observed for carcass-adjusted final BW, DMI, ADG, or G:F. Dietary treatment did not affect (P ≥ 0.11) carcass measurements and distributions of USDA Quality or Yield grades were unaffected by treatment (P ≥ 0.39). Dietary treatment did not affect liver abscess prevalence or severity (P = 0.11). Net energy values calculated from animal performance agreed closely with tabular estimates.

Implications and Applications

Steers fed MDGS as the supplemental protein source did not demonstrate a performance advantage compared with those fed SBM- based protein supplements, despite the enhanced diet conditioning attributes and greater RUP concentrations provided by MDGS.