There is growing interest for including dietary fibre (DF) in pig diets due to its potential health benefits and possible contribution to a reduction of nitrogen (N) excretion from the swine production facility. Different ingredients could be used as the source of DF in swine diets. An experiment was conducted to evaluate the influence of different DF sources with varying indigestible protein (iCP) on bacterial fermentation and associated metabolites (short-chain fatty acids, SCFA) production, and N excretion when used in swine diets. The sources of DF and its iCP content had a major effect on accumulation of ammonia in the colon and N excretion. Peas and pea-fibre based diets decreased N excretion and enhanced bacterial fermentation and SCFA production in the intestine of pigs. Thus, peas and pea-fibres could be considered for swine nutrition, in order to reduce N excretion and potentially improve gut health of pigs, compared to other ingredients studied.