Effects of dietary dilution with fibre on the food intake and gut dimensions of Japanese quail

1. Japanese quail (Coturnix coturnix japonica) were fed on either a conventional diet (low‐fibre) or the same diet diluted with 200 g oak sawdust/kg (high‐fibre). The lengths of the colo‐rectum, small intestine, two caeca combined and empty gizzard weight were measured at 10 and 20 weeks of age. Food intake and rate of passage were measured and an approximate measure of digestibility was also made.

2. There were separate effects of dietary fibre, sex and age on gut size. It was larger in birds fed on high‐fibre diet, in females and in older birds.

3. Increased dietary fibre caused increased food intake, but had no obvious effect on the rate of passage.

4. When quail were fed on the low‐fibre diet or the same diet diluted with 200 or 400 g cellulose powder/kg gut size at 20 weeks of age was greatest when the most fibrous diet was fed and decreased concomitantly with dietary fibre concentration.

5. It appeared that differences in gut size between dietary treatments were more a reflection of variations in food intake than of fibre per se, and that the effects of sex and age on gut size were probably similarly explained.