Digestibility of dried and toasted peas in pigs .1. Ileal and total tract digestibilities of carbohydrates

The ileal and total tract digestibilities of carbohydrates were studied in pigs given diets containing dried or toasted peas (Pisum sativum var. Solara) as the sole source of polysaccharides. Peas from two different harvest years were fed to growing pigs fitted with a cannula at the end of the ileum in two experiments. Two types of cannulas were used in the experiments, a T-shaped cannula designed to collect total digesta and a simple T-shaped cannula. Toasting decreased the ileal digestibility of alpha-galactosides from 98.7 to 96.4% in one harvest of peas and from 65.8 to 41.5% in the other harvest. In vitro studies showed that hydrolysis of pea starch is a relatively slow process. Toasting did not result in gelatinization of starch. However, heat applied in the present conditions did not affect starch digestibility in one of the harvests, whereas a decreased effect was observed in the other. Pea non-starch polysaccharides (NSP) were partially degraded by the distal ileum and had largely disappeared by faecal level, with digestibility values of total NSP between 86.2 and 90.9%. Arabinose and uronic acids were highly digested, whereas glucose and xylose showed lower values. Toasting affected NSP digestibility but its importance was difficult to assess. Moreover, different tendencies were observed in the two harvests of peas: one showing a tendency for increased digestibilities after toasting and the other showing the reverse. It was concluded that different growing conditions or small differences during processing may have affected the digestibility of carbohydrates observed for the dried and toasted peas studied.