Impaired intestinal villi growth in broiler chicks with unhealed navels.

By the time of hatching, the residual yolk sac (RYS) should be completely internalized into the body cavity of the chick via the navel and the navel should be closed (healed). After hatching, the RYS contents are used for general growth and development including growth of the small intestine. This research examined the relationship between the presence of navel buttons (an unhealed navel covered with a scab) and the RYS weight and intestinal villi height of broiler chicks from 0 to 5 d posthatching. Hatching eggs containing live embryos were collected at 18, 19, and 20 d of incubation (n = 5/d). At 21 d of incubation, chicks with healed navels (H) and chicks with navel buttons smaller than 3 mm in diameter (B) were obtained (n = 30/group). The BW and RYS of embryos (n = 5/d) and chicks (n = 5/treatment per day) were weighed. Samples of the small intestine (duodenum and ileum) were processed for histological evaluation to measure villi height. The trial was replicated in time 4 wk after the first collection using eggs and chicks from the same flock. Data were analyzed using SAS PROC MIXED (P < or = 0.05). No significant differences in BW were observed between H and B chicks. Average RYS weight and percentage RYS were greater in B than in H chicks. The interaction of age and navel condition significantly influenced both duodenal and ileal villi heights. On most of the days, duodenal and ileal villi were shorter in B than in H chicks. The presence of small navel buttons at hatching is indicative of impaired absorption of the RYS content and decreased intestinal villi growth. Further research on the relationship between navel buttons, intestinal physiology, and yolk sac infections is advised.