Abstract
This study evaluated distillers grain (DG) by-products produced in different ethanol plants and supplemented in animal diets in Texas, based on samples analyzed from 2008 to 2014. The samples were assessed for concentration, occurrence, and prevalence of selected nutrients and contaminants. Protein and sulfur contents of DG were largely different between corn and sorghum by-products as well as wet distillers grain with solubles and dry distillers grain with solubles (DDGS), indicating a significant effect of grain feedstock and dry-grind process stream on DG composition and quality. Salmonella was isolated in 4 DDGS samples out of a total of 157 DG samples, a percentage (2.5%) that is much lower than the percentage of Salmonella-positive samples found in other feed samples analyzed during the same period. A small amount of virginiamycin residue was found in 24 corn DDGS, 1 corn wet distillers grain with solubles, and 2 sorghum DDGS samples out of 242 samples in total. One sorghum DDGS sample out of 168 DG samples was contaminated with bovine spongiform encephalopathy, but the transmission route of the bovine spongiform encephalopathy agent could not be clearly defined. The concentrations of aflatoxin and fumonisin DG by-products averaged 3.4 μg/kg and 0.7 mg/kg, respectively. Among contaminated corn DG samples, five DDGS samples for aflatoxin contained a higher concentration than the U.S. Food and Drug Administration action level for use in animal feed, whereas no sample for fumonisin was found above the action level. The study results raised some important issues associated with the quality and use of DG by-products, suggesting several approaches and strategies for their effective and safe use as a feed ingredient to promote animal and human health and welfare.