Structural responses of Japanese quail intestine to different diets.

Japanese quail were fed five diets of different nutrient composition and the structural responses of the intestinal tract were measured. Six morphometric variables were recorded. Depending on the diet, we found drastic changes in those factors affecting surface dimensions of the mucosa epithelium and the thickness of the muscle layers of the intestinal wall. We performed a principal component analysis to describe the interrelationship among the different variables and the response of the intestine to different diets. Two principal components were found accounting for surface and muscle layers respectively. Cytokinetic experiments (TdR/BrdU double labelling of S-phase nuclei) were performed to estimate the epithelial turnover time. We found a labelling index between 1.5% and 3% depending on the segment of the intestine. The length of the S-phase was found to be constant along the gut at 6.5 (+/- 2.5) hours. The epithelial turnover time, necessary to rebuild and adjust the intestine, ranged between 10 and 17 days. We discuss evolutionary ecology perspectives as well as applied poultry aspects of the data.