Recovery responses of chick intestinal villus morphology to different refeeding procedures

Recovery responses of intestinal villus height and fine structure on the villus apical surface to different refeeding procedures were compared at refeeding 3 or 24 h after 3-d of feed withdrawal from chicks. After 3-d of fasting, 45-d-old male White Leghorn chicks (Gallus gallus domesticus) were refed rice bran (RB) (CP, 14.8%; ME, 3,170 kcal/kg), conventional grower mash diet (CG) (CP, 18.2%; ME, 2,853 kcal/kg), or ground CG (GG). During the experimental period, birds were given access to diets and water ad libitum. After the end of each experimental period, the duodenum was fixed and examined by light and scanning electron microscopy for morphological changes in the villi. Duodenal villus heights of chicks fasted for 3 d were significantly decreased compared with control chicks fed ad libitum. Villus heights were significantly increased after a 3-h refeeding, and the villi of the GG-refed group were significantly higher than RB and CG. When compared with villus heights at the 3-h refeeding, the RB-refed group showed no changes after a 24-h refeeding, but the CG and GG groups had significantly increased villi heights. Villi heights in GG groups were significantly higher than in the CG groups. Dietary effects on cell area and cell mitosis numbers were similar to those observed for villus height. The surface of the duodenal villi apices of control birds fed ad libitum revealed a clear cell outline, cell protuberances, and cell extrusion into the lumen. After 3-d fasting, cell outlines became faint, and protuberances and extrusion of cells disappeared. After refeeding for 3 h, clear cell outlines were again apparent in all groups. In GG-refed chicks, larger cell outlines and protuberated cells were found as conspicuous morphological features. Similar observations were made at the 24-h refeeding. These morphological findings suggest that chickens that were on feed withdrawal benefit from ad libitum refeeding of a powdered diet that is nutritionally complete for rapid recovery of digestive function.