British Journal of Nutrition

Full Papers

Metabolism and Metabolic Studies

The role of whole-wheat grain and wheat and rye ingredients on the digestion and fermentation processes in the gut – a model experiment with pigs

Maud Le Galla1 p1a2 c1, Anja Serenaa1, Henry Jørgensena1, Peter Kappel Theila1 and Knud Erik Bach Knudsena1

a1 Department of Animal Health, Welfare and Nutrition, Faculty of Agricultural Sciences, Aarhus University, DK-8830 Tjele, Denmark

a2 Agrocampus Ouest, UMR1079 Systèmes d'Elevage Nutrition Animale et Humaine, F-35000 Rennes, France


The effect of wheat and rye breads made from white wheat flour with added refined fibre (WFL), whole-wheat grain, wheat aleurone flour (WAF) or rye aleurone flour (RAF) on digestion and fermentation processes in the gut was studied in a model experiment with pigs. The diets were similar in dietary fibre (DF) but differed in arabinoxylan (AX) content and composition. Twenty pigs were fed the breads three times daily (08.00, 13.00 and 18.00 hours) and the digesta collected through a T-cannula for two successive periods (breakfast: 8.00–13.00; lunch: 13.00–18.00 hours). Faeces were collected for 24 h and caecal and colonic contents at slaughter. The rigid nature of the aleurone cell walls encapsulated nutrients, which resulted in reduced (P < 0·01) digestibility of protein (WAF and RAF breads) and fat (RAF bread). For the RAF bread, the digestibility of starch was also lower (P < 0·001) than of the wheat-based diets primarily due to the higher intestinal viscosity. The DF composition had an impact on (P < 0·001) the site for fibre degradation in the large intestine. Thus, AX of the WAF bread, with the lowest degree of substitution, were fermented as much in the caecum as in the colon, whereas AX of the RAF bread, with an intermediary degree of substitution, were mainly fermented in the caecum. The WFL bread, rich in cellulose, was fermented more distally. Fermentation of experimental breads in the large intestine had no effect (P>0·05) on the production of metabolites, except for butyrate which was higher (P < 0·01) after the WAF bread consumption.

(Received January 12 2009)

(Revised June 09 2009)

(Accepted June 11 2009)

(Online publication July 27 2009)


c1 Corresponding author: Dr Maud Le Gall, fax +33 223485080, email

p1 Present address: INRA, UMR1079 Systèmes d'Elevage Nutrition Animale et Humaine, F-35590 Saint-Gilles, France


Abbreviations: AX, arabinoxylan; DF, dietary fibre; GIT, gastrointestinal tract; RAF, rye aleurone flour; WAF, wheat aleurone flour; WFL, wheat flour; WWG, whole-wheat grain