Effects of luminal nutrient absorption, intraluminal physical stimulation, and intravenous parenteral alimentation on the recovery responses of duodenal villus morphology following feed withdrawal in chickens

The aim of this study was to clarify which of the-following three factors induces villus morphological recovery best: enteral nutrient absorption, intraluminal physical stimulation, or intravenous parenteral alimentation. At 142 d, male White Leghorn chickens (Gallus gallus domesticus) were divided into eight groups of five birds each as follows: 1) access given ad libitum to a commercial layer mash diet (CP, 17.5%; ME, 2,830 kcal/ kg) (control), 2) 5-d feed withdrawal (feed withdrawal), 3) 3-d feed withdrawal (3-FW), followed by refeeding the same diet:as the control for 2 d (refeeding), 4) 3-FW followed by force-feeding enteral hyperalimentation (enteral), 5) 3-FW followed by force-feeding an indigestible (nonabsorbable) substance (kaolin), 6) 3-FW followed by force-feeding water for 2 d (force-fed control), 7) 3-FW followed by parenteral hyperalimentation (parenteral), and 8) 3-FW followed by no alimentation (sham control) for 2 d. In the refeeding and enteral groups, BW significantly recovered (P < 0.05), and in the parenteral group, BW tended to increase, suggesting that nutrients were enterally and parenterally absorbed, respectively. The BW in the remaining three groups showed a significant decrease (P < 0.05), indicating that kaolin could not be absorbed enterally. Compared with the feed withdrawal group, villus height, cell mitosis, and villus tip surface morphology of refeeding and enteral groups exhibited rapid villus morphological recovery. Villus morphological recovery of the enteral group appears to have been caused by enteral nutrient absorption. However, villus morphology in the kaolin treatment was not different from that in the feed withdrawal group, which suggests that intraluminal physical stimulation had no effect on villus morphological recovery. On the other hand, the parenteral group showed no effect on villus morphological recovery, which suggests that the parenteral nutrient supplied to the villi via the blood could not induce villus morphological recovery; the intestinal mucosal atrophy might have been caused by the absence of enteral nutrients, and would only be stimulated by enteral nutrient absorption. In conclusion, the present findings suggest that villus morphology is governed neither by intraluminal physical stimulation nor by parenteral alimentation, but by enteral nutrient absorption.