Previous work has shown that equids generally have lower apparent digestibilities in vivo compared to ruminants. This observation may be due to either; (1) higher rates of passage through the digestive tract of equids compared to ruminants; (2) less opportunity for absorption of microbial digestion end products following hindgut fermentation in equids compared to foregut fermentation in ruminants; or (3) to caecal and colonic micro-organisms in equids being less efficient at feed constituent degradation compared to ruminal micro-organisms. To test this latter possibility, this experiment examines the hypothesis that feed constituents will be degraded to a similar extent when exposed to either an equid hindgut or a ruminal foregut microflora for the same time periods.