Dry milling ethanol by-products for animal feed

Dry milling ethanol plants represent the fastest growing segment of the fuel ethanol industry in the USA, and produce the majority (60%) of fuel ethanol. In South Africa it is expected that all plants to be erected will utilize the dry milling process to produce ethanol from maize. Starch, the major fraction in maize is converted to ethanol and carbon dioxide in the dry milling process. The remaining nutrients are protein, fat, minerals and vitamins that will be concentrated in various ways to end up in the different by-products, which include wet (WDG) and dry distiller's grains (DDG), wet (WDGS) and dried distiller's grains (DDGS) with solubles, modified "wet cake" (a blend of wet and dry distiller's grains), and condensed distiller's solubles (CDS). Although in this paper distiller's grains will be referred to as by-products due to the fact that ethanol makes up the major portion of revenues of the dry milling process, they should in fact be called co-products, since there sales are an important part of the total profitability of such a plant. These products have important nutritional properties and may offer the animal feed industry a tremendous opportunity to reduce feed costs without sacrificing performance. However, there are significant challenges that must be met before feeding these products.