Morphologic alterations in small intestinal epithelium of lambs fed vitamin A-depleted diet

Ten crossbred wether lambs were fed once daily an oat diet that contained 3102 micrograms of retinyl palmitate (control) and were supplemented with 55,000 micrograms of retinyl palmitate orally once every two weeks. Twenty lambs were fed the same oat diet without retinyl palmitate supplements (A-depleted). After being fed the A-depleted diet for 28 weeks, 10 A-depleted lambs were repleted by feeding the control diet and oral supplementation of retinyl palmitate for eight weeks. The A-depleted lambs had serum vitamin A concentrations indicative of vitamin A deficiency, which was supported by very low liver vitamin A concentrations. Light microscopic and ultrastructural examinations revealed that alterations occurred at 50% and 75% of the small intestine length in A-depleted lambs only. Sawtooth configuration of the intestinal epithelium was a distinctive histologic feature. Consistent ultrastructural alterations were vesicular microvillar degeneration and disruption of the capillary endothelium. These results suggests that A-depleted diets have a detrimental effect on the small intestinal epithelium of lambs. Vitamin A repletion appears to minimize the detrimental effects.