The effect of weaning diet on the subsequent colonic metabolism of dietary fibre in the adult rat.

The effect of the weaning diet on the subsequent colonic metabolism of bran and pectin in the adult rat has been investigated. Feeding a fibre-reduced diet on its own or supplemented with bran (WB) and pectin (P) from weaning (fibre-reduced (weaning)) was compared with introducing the same diet to age-matched rats reared on a standard laboratory diet from weaning (fibre-reduced (6 weeks)). The effects of the diets on colonic metabolism were measured by wet and dry caecal contents and stool weights, caecal sac weight, and caecal and faecal short-chain fatty acids (SCFA). Final body-weights were greater for fibre-reduced (6 weeks) and fibre-reduced (6 weeks) + P groups, but not fibre-reduced (6 weeks) + WB, than those of the fibre-reduced (weaning) rats. Rats fed on fibre-reduced (6 weeks) diet had a higher total caecal SCFA content than fibre-reduced (weaning) control rats. Fibre-reduced (weaning) + P-fed rats had a threefold higher caecal concentration of both propionate and butyrate than the matched fibre-reduced (6 weeks) + P group. Fibre-reduced (weaning) + WB animals had a significantly higher butyrate caecal concentration compared with their matched fibre-reduced (6 weeks) + WB group. Fibre-reduced (weaning) + P-fed rats had a lower faecal output than the fibre-reduced (6 weeks) + P rats. There was no difference in faecal output in rats fed on either fibre-reduced (6 weeks) + WB or fibre-reduced (weaning) + WB. The faecal concentration of SCFA was in general higher in the rats fed on fibre-reduced (weaning) alone, + P, or + WB than in those fed on fibre-reduced (6 weeks) alone, + P or + WB. Faecal output of total and individual SCFA was increased on the fibre-reduced (weaned) + WB diet compared with fibre-reduced (6 weeks) + WB-fed animals. The diet at weaning may be important in determining the pathways of caecal bacterial metabolism in the adult rat. In studying the effect of a dietary fibre on caecal metabolism and faecal output, when the diet is changed appears to be important.