The objective of this study was to evaluate the fermentation characteristics of some non-conventional feed ingredients with varying fermentable fibre and their possible influence on intestinal environment and nitrogen excretion, in the intestines of pigs, using an in vitro technique. We concluded that fibre fermentation characteristics in the pig gastrointestinal tract are extremely variable from one ingredient to another. Of the feed ingredients evaluated, peas and pea fibres had higher fermentability and bacterial protein synthesis capacity,