The digestible (DE) and net energy (NE) content of peas in pigs is very variable and that variability mainly depends on genetic and environmental factors. On the contrary, it can hardly be explained by differences in chemical composition. In order to find out an explanation, other factors such as the rate of starch hydrolysis in the small intestine or the rate of fibre fermentation in the large intestine were investigated and the results were correlated to the DE content of the peas and their chemical composition. Laboratory techniques that mimic the digestive and fermentative processes in the pig’s digestive tract were used to try to find an explanation. The results showed a wide range of variation in starch hydrolysis in the small intestine but no variation in fibre fermentation in the large intestine between pea varieties grown in different conditions. Moreover, no correlations were established either between the chemical composition and the rate of starch hydrolysis or between starch hydrolysis and the digestible energy content.