Table 4

Susceptibility to azoxymethane (AOM) of rats fed experimental diets (low fibre control diet (CD), starch free wheat bran enriched diet (WB), type III resistant starch enriched diet (RS), and short chain fructo-oligosaccharide enriched diet (FOS)) for 44 days

  • Two batches of six week old rats (A, n=16; B, n=20) were successively included in the study within a two week period. Rats were housed four per cage (randomly constituted blocks) until the beginning of the nutrition study, and then one per cage. They were first fed UAR A04 (pellets then powder), and then from D0 (10 weeks old) the powdered experimental diet allocated by randomisation. On D44, rats were injected twice subcutaneously, one week apart, with 15 mg/kg AOM. For each batch, rats were sacrificed one month later, at a rate of one or two blocks a day, that is, aberrant crypt foci (ACF) were scored 30–32 days after the first injection. The colon was separated longitudinally into two parts, only one was used for ACF count. The part kept for ACF count was divided into proximal and distal colon (according to the orientation of the mucosal folds), the latter being subdivided into two equal parts (upper and lower). ACF and individual crypts inside were scored, and then the total number of aberrant crypts (AC) were calculated. The AC/ACF ratio is indicative of crypt multiplicity.

  • Results were analysed using the ANOVA modelY=diet+batch, followed by Bonferroni's test. The batch effect was always significant (p <0.001) whereas the diet effect was significant only for ACF.