160. Effects of Replacing Corn Silage with Alternative Roughages in Grain-Based Diets Fed to Beef Steers.

Abstract

Corn silage is the predominant roughage source for cattle operations around the U.S. However, alternatives, such as forage sorghum baleage and wheatlage, may benefit some producers. The objectives of this study were to investigate the impacts of replacing corn silage with forage sorghum baleage or wheatlage in grain-based diets for beef steers. Steers (n = 108; initial BW = 461 ± 37 kg) from 2 farms were transported to the feedlot. After 21-d transition period to the grain-based diets, steers were stratified by body weight (BW) and farm and assigned to 1 of 3 dietary treatments: corn silage (n = 36; CORN), forage sorghum baleage (n = 36; SORG), or wheatlage (n = 36; WHEA). Diets included dry-rolled corn, soybean meal, and distillers dried grain soluble and were formulated to supply similar dietary neutral detergent fiber (NDF = 14.5% dry matter (DM) basis). Diet particle size was measured monthly using a Penn State Particle Size Separator, and physically effective fiber (peNDF) was estimated. Individual dry matter intake (DMI) was recorded using the GrowSafe intake monitoring system (Vytelle, Alberta, CAN). Fecal samples were collected at three different time points to be analyzed for NDF and DM digestibility (NDFD and DMD). Steers were fed to a target final BW of 660 kg. Carcass characteristics, such as hot carcass weight (HCW), 12th rib fat (RF), marbling score, dressing percentage (DP), ribeye area (REA), and yield grade (YG), were collected 3 d post-slaughter. Data were analyzed using MIXED and GLIMMIX procedures of SAS 9.4. Estimated peNDF did not differ (P = 0.06) among treatments. Steers fed SORG and WHEA gained 0.11 and 0.09 kg/d more (P = 0.04), than steers fed CORN. Steers fed SORG ate more (P = 0.02; 12.52 kg DMI/d) when compared to steers fed WHEAT and CORN (12.34 and 11.92 kg DMI/d, respectively), but feed efficiency (gain : feed) did not differ (P = 0.67). Steers fed SORG had a better NDF digestibility (P < 0.01; 73.67%) compared to steers fed CORN (69.14%) and WHEA (69.04%). There were no treatment differences (P > 0.05) for HCW, RF, DP, REA, or YG. However, steers fed CORN and SORG had 45 and 42 points, respectively, greater marbling scores (P = 0.01) than steers fed WHEA. Cattle can be fed alternative forages to corn silage without compromising growth and carcass performance traits.