In this thesis Distillers Dried Grains and Solubles (DDGS) were analyzed by Fourier Transform Infrared spectroscopy (FT-IR spectroscopy) and Isotope Ratio Mass Spectrometry (IRMS). The aim was to develop authentication strategies for DDGS in terms of botanical origin, geographical origin, and method of production. In summary, FT-IR spectroscopy and IRMS showed to be suitable analytical techniques for authentication of DDGS with regards to their botanical and geographical origin, however no appropriate strategy with regards to the method of production was found. Moreover, it was demonstrated that FT-IR spectroscopy could be used as screening technique for the quantitative analysis of crude fat and sulfates in DDGS. In the future, the analytical procedures and authentication strategies developed in this thesis could be transferred to authentication of other animal feed ingredients.