Nutritional value and utilization of wheat dried distillers grain with solubles in pigs and poultry.

Dried distillers grain with solubles (DDGS) are a co-product of ethanol production from starch cereals (mainly maize in North America and wheat in Europe), which contains approximately the non-starch or non-fermentable fractions of the grain. As more becomes available with increasing bio-ethanol production, DDGS is being included not only in diets for ruminants but also in pig and poultry diets. This review paper considers the introduction possibilities of wheat DDGS in poultry and pig diets. Nutrients content in wheat DDGS and digestibility vary among ethanol plants, reflecting the starch extraction process and drying of the residues after starch extraction. Most of the variability concerns amino acid (AA) contents and their standardized ileal digestibility (SID), affected by the occurrence of Maillard reactions, reflected in the lightness score (L) of wheat DDGS. Samples with low L values (<50) are dark and have the lowest nutritional value, both in pigs and in poultry. Lysine is the most affected AA, with contents ranging between 0.9 (dark) and 3.0 percent of crude protein (CP; N×6.25) for wheat DDGS. In parallel, lysine SID is also variable, with the lowest values observed in DDGS with low lysine level in CP. For the darkest products, lysine SID is close to zero. Energy digestibility varies in parallel with changes in lysine content and L values, but is more related to other nutrients such as dietary fibre, fat and residual starch contents. In addition, wheat DDGS can supply significant amounts of available phosphorus. DDGS from wheat can be used in diets for poultry and pigs; however, in relation with nutritional value variability, practical use should take into account correct energy values or lysine SID content in order to prevent any performance deterioration. Finally, only the light-coloured products are recommended for non-ruminants, and their introduction at high inclusion rates will contribute to reducing the energy value of the diet. Biofuel co-products as livestock feed – Opportunities and challenges 164 composition of the grain. Consequently, the nutrients, except starch, would be expected to be approximately three fold higher in wheat DDGS than those in the original grain (Table 1). However, in practice, the chemical composition of wheat DDGS is much more variable than in the original cereals, with large differences among ethanol plants according to the method of grain preparation, namely with or without previous dehulling; the fermentation process; the amount of soluble fractions blended with distillers grain; the duration and temperature of drying; and possible further fractionation of the non-starch fractions (separation of proteins, etc.) (Belyea, Rausch and Tumbleson, 2004). There are two main technologies in use, resulting in co-products with different starch content (Cozannet et al., 2010a). The first involves entire grain grinding and fermentation, leaving a low-starch-content DDGS (<7%); whereas in the other process wheat bran is removed, leaving a higher-starchcontent DDGS (>7%). In addition, reflecting the technical aspects among and within processes, the colour of DDGS can vary from light yellow to dark brown (Photo 1). Measured with a Minolta colorimeter, luminance (L) values of 10 European wheat DDGS ranged from 43 (black products) to 63 (yellow products) in the study of Cozannet et al. (2010a). From their results it can be inferred that wheat DDGS with L values <50 have been overheated, with a high incidence of Maillard reactions. This agrees with previous recommendations for maize DDGS (Cromwell, • Wheat DDGS, a co-product of the wheat ethanol industry, contains high levels of crude protein (ca 30 percent), but with a low and variable content of lysine. This variability in lysine level is dependent on the ethanol production process and the heat damage occurring during the DDGS drying process. • In both pigs and poultry, the ileal digestibility of lysine in DDGS is lower than in wheat, and is also quite variable, with the lowest values in heat-damaged