Vitamin A deficiency induces morphometric changes and decreased functionality in chicken small intestine

The effect of vitamin A on chicken intestinal mucosal morphology and functionality was tested in relation to severe and mild vitamin A deficiency and vitamin A repletion. Compared with rats and mice, chickens have a very quick response to a deficient dietary intake. Severe vitamin A deficiency altered the small intestine of chickens at both the biochemical and the morphological levels. It caused the loss of mucosal protein, reduced villus height and crypt depth and diminished activities of disaccharidases, transpeptidase and alkaline phosphate (EC 3.1.3.1). The ratios RNA:DNA, RNA:protein and protein:DNA, and the DNA concentrations in 1 g intestinal tissue, together with morphological measurements, provided knowledge about the pattern of lesion. The results indicated that (1) lack of vitamin A influenced cellular hyperplasia as it caused an increase in DNA content and in the number of enterocytes per villus; (2) lack of vitamin A influenced cellular hypertrophy as it decreased the protein:DNA ratio. There was no difference in mucosal enzyme activity between the two deficient groups. The repletion group exhibited a remarkable increase in mucosal enzyme activity only 4 d after switching to the control diet. The evidence presented in our paper suggests that the low vitamin A supply interferes with the normal activity of chicken intestinal mucosa as it influences the processes of proliferation and maturation of enterocytes.