Evaluation of Canola Meal Versus Soybean Meal As a Protein Supplement on Performance and Carcass Characteristics of Growing and Finishing Beef Cattle

Two trials were conducted to evaluate the performance and carcass characteristics of backgrounding and finishing cattle fed canola meal (CM) versus soybean meal (SBM) as a protein supplement with or without wheat dried distillers’ grains with solubles (WDDGS). Trial 1 was a 95-d backgrounding program in which 398 steer calves (288±0.27 kg; mean±SE) were assigned to one of 12 pens and fed one of four barley silage, barley grain-based diets formulated to 13.5% CP, and 1.52 and 0.92 Mcal kg^-1 NE_m and NE_g, respectively. The dietary treatments included: CM (8.7% DM), SBM (7.0% DM), CM+WDDGS (4.6 & 4.8% DM), and SBM+WDDGS, (4.2 & 4.4% DM). Trial 2 utilized 300 head (306±0.94 kg) assigned to 25 pens for a 61-d backgrounding and 147-d finishing program. Backgrounding diets were identical to Trial 1 with the addition of a fifth treatment (WDDGS, 9.5% DM). The basal finishing diet was barley grain-based and formulated to 13% CP, and 1.95 and 1.30 Mcal kg^-1 NE_m and NE_g, respectively. The five dietary treatments included: CM (5.7% DM), SBM (4.3% DM), CM+WDDGS (3.0% & 3.1% DM), SBM+WDDGS, (2.4% & 2.6% DM), and WDDGS (6.7% DM). Performance results for each trial were analyzed as a completely randomized design using the Mixed model procedure with pen as the experimental unit. Quality and yield grades were analyzed using GLIMMIX with a binomial error structure and logit data transformation. In trial 1, there were no differences between treatments for final BW (420.7±1.8 kg; P= 0.30), or gain-to-feed (G:F) (0.16±0.003; P= 0.60); however, ADG was greatest (P< 0.05) for cattle fed SBM relative to cattle fed SBM+WDDGS (1.45±0.04 kg vs. 1.32±0.03 kg). In trial 2, no treatment differences (P > 0.22) were detected for ADG (1.65±0.01 kg), DMI (9.77±0.07 kg), or G:F (0.17±0.001). Cattle fed SBM+WDDGS had the least subcutaneous fat depth relative to cattle fed CM+WDDGS (1.17±0.06 cm vs. 1.46±0.05 cm; P = 0.02) and the poorest marbling score relative to cattle fed WDDGS (398.75±15.19 vs. 440.10±8.20; P = 0.05). There was a tendency (P= 0.09) for greater proportion of AAA carcasses with the WDDGS treatment (66.1±6.2%) while SBM+WDDGS had the least (41.4±6.5%). These results indicate that CM is equal to SBM as a protein supplement for backgrounding and finishing cattle and that provision of WDDGS as a source of rumen undegradable protein did not benefit performance. The combination of SBM+WDDGS negatively influenced energy partitioning to carcass fat deposition.