Because digestion and absorption of ingested feed
occurs in the small intestine, intestinal structure is
assumed to be related to its function. In intact chickens,
the shape of intestinal villi is twofold and includes
tongue- and leaf-shaped villi (Van Leeuwen et al., 2004).
However, belt-like villi encircling the jejunal lumen were
also observed in chickens subjected to jejunal resection
(Fig. 1) (Yamauchi, 2002). This abnormal shape was
induced by intestinal enlargement (diameter, about 4
cm) just proximal to an end-to-end suture that showed
abnormal intestinal stricture resulting from transit malfunction
of intestinal contents. The abnormal villus development
might be induced by long-term retention of
intestinal contents, including hypernutrients.
Similarly, intestinal villi in intact chickens gradually
decrease in length (Rolls et al., 1978) and size (Altmann
and Leblond, 1970) moving from the duodenum to the