Effect of increasing distillers grains inclusion on performance and carcass characteristics of early-weaned steers1

Abstract

Dried distillers grains with solubles (DDGS) contain elevated concentrations of CP, oil, and S, which can negatively impact performance and carcass characteristics in steers weaned at 205 d of age. Early weaned (EW) cattle, however, consume less DM and require increased CP. Furthermore, the energy required to dispose of excess N may actually decrease excessive fat accumulation, which can occur in EW cattle. Thus, we hypothesized that feeding diets with increased concentrations of DDGS to EW steers for the first 99 d would decrease fat thickness and increase harvest weights, and would not inhibit performance or marbling deposition. To test this hypothesis, 90 Angus × Simmental steers (199.7 ± 12.2 kg) were weaned at 134 d of age (EW) and allotted to 3 high concentrate diets (20% corn silage) containing either 0%, 30%, or 60% DDGS (15.7%, 15.8% and 21.7% CP, respectively). Dietary treatments were fed for 99 d, after which steers were placed on a common diet containing no DDGS (12.9% CP) until harvest at a common weight of 599 kg. Concentration of dietary DDGS did not affect ADG, DMI, or G:F during the growing phase (P > 0.41), did not produce any carryover effects on ADG, DMI, or G:F during the finishing phase (P > 0.26), and resulted in similar overall performance (P > 0.52). Dressing percentage (P < 0.05), HCW (P = 0.06), fat thickness (P = 0.10), and % KPH (P = 0.08) responded quadratically to early DDGS supplementation, increasing from 0 to 30% DDGS inclusion and decreasing from 30 to 60% DDGS inclusion, respectively. Marbling score was not affected (P > 0.46) by DDGS inclusion, but there was a tendency (P = 0.08) for the ratio of subcutaneous (SC) to intramuscular (IM) fat to be altered by DDGS inclusion. The ratio of IM to SC fat decreased from 0 to 30% DDGS inclusion and increased from 30 to 60% DDGS inclusion. These data suggest that inclusion of increased concentrations of dietary DDGS early in the feedlot phase does not negatively impact growth and performance of EW cattle, but does partition energy from carcass to noncarcass components. However, increased concentrations of DDGS did not negatively impact IM fat deposition. Utilization of energy for disposal of excess N may be responsible for changes in carcass weight and SC fat deposition.