Dietary fibre and mixed link ß-glucans found within oats and barley may reduce the risk of cardiovascular disease and colorectal cancer. Little is known about how oat fibre consumption influences the gut microbiota. Here we investigated the effects of enzymatically pre-digested oats on microbial activity and composition using a combination of in vitro techniques. Pure culture and batch culture experiments identified specific bacteria could grow on oat fibre. Fermentor experiments identified Roseburia spp., Lactobacillus spp. and Desulfovibrionales spp. were found in greater numbers specifically in the mucin environment, while Bacteroides spp. and F. prausnitzii were more abundant in the liquid environment. Time had a significant impact on both butyrate production and the abundance of butyrate producing species. Differences in the output of short chain fatty acids (SCFA) between experimental conditions was apparent. In batch culture systems butyrate was the most abundant SCFA detected from oat fibre fermentation compared to acetate in the fermentor system. Oat fibre was more fermentable under higher pH conditions and more SCFA were detected at pH 6.5 compared to 5.8. This suggests that in vivo most of the fermentation of oat fibre may likely take place in the distal colon. Bacteroides spp. are known to prefer higher pH conditions, such as those found in the distal colon, and grew consistently on oat fibre. All cereal samples used were obtained from Orkney College, and detailed agronomic and nutritional analysis was performed on different cultivars of oats and barley as part of this project. Cereal trials identified that Scandinavian oat and barley cultivars were viable alternatives to native Scottish crops for growers in the North of Scotland. Scandinavian cultivars produced higher yields, thousand grain weights and had a similar growing period to cultivars more regularly grown in Scotland. As expected the environment has a bearing on the nutritional and agronomic performance of cultivars, in terms of yield and protein and starch content.