Performance and Digestibility Characteristics of Finishing Diets Containing Distillers Grains, Composites of Corn Processing Coproducts, or Supplemental Corn Oil

Three experiments evaluated the lipids in distillers grains plus solubles compared with corn or other sources of lipid in finishing diets. Experiment 1 utilized 60 individually fed yearling heifers (349 ± 34 kg) fed treatments consisting of 0, 20, or 40% (DM basis) wet distillers grains plus solubles (WDGS), or 0, 2.5, or 5.0% (DM basis) corn oil in a finishing diet based on high-moisture corn (HMC) and dry-rolled corn (DRC). Cattle fed 20 and 40% WDGS had greater (P \u3c 0.10) G:F than cattle fed 0% WDGS. Cattle fed the 5.0% corn oil had lower overall performance than cattle fed the other diets. Results from Exp. 1 indicated that adding fat from WDGS improves performance, whereas supplementing 5.0% corn oil depressed G:F, suggesting that the fat within WDGS is different than corn oil. Experiment 2 used 234 yearling steers (352 ± 16 kg) fed 1 of 5 treatments consisting of 20 or 40% (DM basis) dry distillers grains plus solubles (DDGS), 1.3% or 2.6% (DM basis) tallow, or HMC. All diets contained 20% (DM basis) wet corn gluten feed (WCGF) as a method of controlling acidosis. No differences between treatments for any performance parameters were observed in Exp. 2. The DDGS may be similar to tallow and HMC in finishing diets containing 20% WCGF. Experiment 3 used 5 Holstein steers equipped with ruminal and duodenal cannulas in a 5x5 Latin square design. Treatments were a 40% WDGS diet, 2 composites, one consisting of corn bran and corn gluten meal (COMP), and one consisting of corn bran, corn gluten meal, and corn oil (COMP + OIL), and 2 DRC-based diets supplemented with corn oil (CON + OIL) or not (CON). Cattle fed the WDGS diet had numerically lower rumen pH compared with cattle fed other treatments. Cattle fed WDGS had greater (P \u3c 0.10) molar proportions of propionate, lower (P \u3c 0.10) acetate:propionate ratios, greater (P \u3c 0.10) total tract fat digestion, and a greater (P \u3c 0.10) proportion of unsaturated fatty acids reaching the duodenum than cattle fed other treatments. Therefore, the higher energy value of WDGS compared with corn may be due to more propionate production, higher fat digestibility, and more unsaturated fatty acids reaching the duodenum