Nutrient Variability of Distillers Grains with Solubles

Breitling, B.J. and K.J. Herrick, POET LLC, Sioux Falls SD

Distillers grains with solubles (DDGS) is an ingredient that is commonly included in livestock ration formulations. Several reasons for the widespread use of DDGS include a favorable nutrient profile, competitive cost, and availability. However, as with all co-products, one reason for exclusion from ration formulation is a concern regarding variability. It was our objective to address this concern by characterizing the quality of DDGS across 27 ethanol biorefineries within the POET (Sioux Falls, SD) system. As part of the quality control process, all POET biorefineries periodically collect samples of DDGS which are then sent to a third-party laboratory for nutrient analysis. The 2 most recent years of this data was summarized and analyzed using JMP® Pro software (version 11.21.1, SAS Institute, Cary, NC). Main nutrients in the analysis included: dry matter (DM), crude protein (CP), ether extract (EE), acid detergent fiber (ADF), neutral detergent fiber (NDF), crude fiber, and S. Evaluation within JMP was completed using the Multivariate Chart option which focuses on descriptive statistics. In addition, the Variance Components with Main Effects option was used to give a variability estimate for location, time, and inherent variability. This value provided a percentage of the variance explained by all main effects. Time explained 25.6% of the variability in DM (89.2 ± STD 1.13%) while location accounted for only 7.1% of the variability. Typically, DM is intentionally adjusted during different seasons in order to optimize physical handling characteristics. Averages and standard deviations for CP (30.7 ± 1.57% DM), EE (5.36 ± 0.96% DM), ADF (10.6 ± 1.76% DM), NDF (27.8 ± 3.27 DM), crude fiber (8.31 ± 0.82% DM), and S (0.92 ± 0.13% DM) were all within POET’s quality assurance ranges. Differences between locations explained 38.9, 12.5, 11.1, 17.2, 14.8, and 25.5% of the variability for CP, EE, ADF, NDF, crude fiber, and S, respectively. Time explained the majority of variability for ADF (43.6%) and NDF (50.1%); however, after review of the data, it was apparent that a February 2015 change in the third-party laboratory resulted in greater estimates of ADF and NDF. This data demonstrates that DDGS produced by the POET biorefinering system during the previous 2 years has a very consistent nutrient profile. It also demonstrates that factors other than location and time account for a majority of the variability. As a result, nutritionists can be confident when formulating rations that DDGS sourced from a POET biorefinery will provide a consistent supply of nutrients.