RESUMEN
BACKGROUND: Dried distillers' grains with solubles (DDGS) are becoming increasingly available and popular as an alternative livestock feed. This study used continuous and batch culture techniques to compare the in vitro fermentation characteristics of diets containing corn-, triticale- or wheat-based DDGS at 200 g kg(-1) diet dry matter (DM) against a barley grain-based control diet. RESULTS: In continuous fermentation of wheat DDGS diet, total volatile fatty acid (VFA) concentration was decreased by 15.7% across sampling times and NH(3) concentration was quadrupled compared with control, whereas fermentations of corn- and triticale-DDGS diets were similar to the barley-based control. In batch cultures, corn DDGS differed from control only in increased culture pH. Compared with control diet, triticale DDGS yielded lower total gas production (140.94 versus 148.78 mL g(-1) DM) and in vitro DM digestibility (IVDMD; 0.509 versus 0.535). Wheat DDGS diet yielded decreased total gas production (123.49 mL g(-1) DM) and IVDMD (0.468), as well as total VFA production (105.84 versus 134.20 mmol L(-1)) and substantially increased ammonia concentration (151.61 versus 58.34 mg L(-1)) and acetate:propionate ratio (2.94 versus 1.11). CONCLUSION: Corn- and triticale- DDGS diets exhibited fermentation characteristics similar to the barley based control diet, consistent with in vivo findings that these diets yielded no adverse effects on production. In vitro ruminal fermentation of wheat DDGS diet differed significantly from control in several aspects including 2.6 to 6X higher ammonia concentrations.