Sources of variation in composition of DDGS

High protein and high energy content make distillers dried grains with solubles (DDGS) a unique ingredient for ruminant diets, but variation in composition reduces nutritional quality and market value. There is little published information that addresses the specific causes of variation. Samples of DDGS from dry grind processing (ethanol) plants in the upper Midwest were analyzed for nutrient concentrations and sources of variation were evaluated.Significant plant × period (time) interactions indicated that variation was associated with specific fermentation batches, rather than plants or time (periods) per se. Differences in maize characteristics and in processing conditions probably were responsible for batch to batch effects. Fat content of DDGS samples was relatively uniform, but there was considerable variation in protein concentration (260–380 g/kg DM). Low lysine (8.9 g/kg DM) and elevated pepsin insoluble (bound) protein concentrations were additional concerns. Published values for ruminally undegradable protein content were as accurate as estimates using specific plant data.