Growing System Effects on Silage Type Selection for the Finishing Phase of Beef Steers: Feedlot Growth Performance, Carcass Characteristics, Nutrient Digestibility, and Feeding Behavior

The effects of beef cattle growing systems on type of silage during the finishing phase were assessed based on growth performance, carcass characteristics, digestibility, and feeding behavior. Steers (n = 128; BW = 394 ± 21 kg) were used in a 2 × 2 factorial treatment arrangement: a) growing system (Grazing [forage sorghum bmr-6 AF7401]; or Bunk-fed [65% concentrate diet]); and b) finishing diet silage source (Corn silage [BH8895]; or Sorghum silage [bmr-6 AF7401]) 20% inclusion (DM basis). Pen (n = 8 per treatment) was the experimental unit during the finishing phase and a split plot experimental design was used. Only descriptive data was recorded during the growing system phase. No interactions (growing system × finishing phase silage type) were observed (P > 0.16). Steers that grazed had greater ADG (P < 0.01), DMI (P < 0.01), and G:F (P < 0.01) during the finishing phase, than bunk-fed steers. Greater HCW (P < 0.01), less DP (P < 0.01), and less 12th-rib fat (P < 0.01) were observed for steers grown on the forage sorghum grazing system than Bunkfed steers during growing phase. Regardless of growing system, steers fed the corn silage-based finishing diet had less DMI (P < 0.01), greater G:F (P < 0.01), and tended (P = 0.06) to have greater ADG during the finishing phase than steers fed the sorghum silage-based finishing diet. The corn silage-based finishing diet had greater digestibility of nutrients (P < 0.01) than the sorghum silage-based finishing diet, except by fiber, which was not different (P > 0.12) among treatments. Sorghum grazing during growing phase positively affected growth performance during the finishing phase. Replacing corn silage with sorghum silage in beef finishing diets at inclusions used in current study requires diet energy adjustments.