Distillers grains with solubles for feedlot cattle---finishing performance, lipid metabolism, and ethanol greenhouse gas balance

Previous University of Nebraska feedlot research trials have characterized the feed value of wet distillers grains plus solubles (WDGS). These trials were summarized with meta-analysis methodology and indicated the feed value of WDGS interacts with corn processing type, cattle age (calf-fed or yearling), and inclusion level. Two steer finishing studies and a metabolism study were conducted to understand the impact of different lipid sources in WDGS on WDGS feed value. A biphasic lipid extraction procedure was developed to analyze feed samples from these trials that was more effective than Goldfisch ether extraction at lipid analysis of byproduct feds. These trials indicated the lipid content of WDGS partially accounted for WDGS feed value being greater than corn. Diets containing WDGS to supply up to 8% of diet DM as lipid may be fed without depressing cattle performance. However, feeding diets containing 8% dietary lipid with corn oil depresses cattle performance. The difference in rumen metabolism of these two lipids is due to partial physical protection of WDGS lipid from metabolism by rumen microbes. However details for the mechanisms for the improved feed value of WDGS relative to corn are still unknown.;Key Words: Beef cattle, Byproducts, Distillers grains, Lipid...