Development of the digestive tract in the ostrich (Struthio camelus)

A study was conducted to investigate changes in the development of the gastrointestinal tract (GIT) in relation to body growth of growing ostriches. There was an 11-fold increase (P < 0.001) in body weight between 3 and 72 days of age. The relative (to body weight) weight of the proventriculus/gizzard, caeca and colon also increased (P < 0.001) with age. The relative weight of the small intestine peaked at 41 days of age and then tended to decline (P < 0.05) subsequently. The relative weight of the pancreas peaked at 27 days of age and remained fairly stable thereafter. The activities of chymotrypsin and lipase declined (P < 0.001) with age between 3 and 72 days. At 3 days of age, the protein content of the duodenal mucosal homogenate was higher (P < 0.001) than that of the jejunum or ileum, but at all subsequent periods the jejunal protein content was the highest. The protein content of the intestinal brush-border membrane was higher (P < 0.001) at the jejunum than at the duodenum or ileum. The specific activity of maltase declined (P < 0.001) with age in all three regions, most especially between 3 and 27 days of age. The activity of alkaline phosphatase (AP) at 41 and 55 days of age was higher (P < 0.001) in the duodenum than in the jejunum or ileum. The activity of AP fluctuated with age in the duodenum but there was a more defined decline (P < 0.001) with age in the jejunum and ileum. The relative protein content of the liver increased (P < 0.001) with age, with two peaks at 27 and 55 days of age. Arginase activity was not detected in the liver of 3-day old chicks and was not significantly affected by age between 27 and 72 days of age. The pattern of development observed is similar to that in growing poultry. There is, however, a need for evaluation at closer intervals in early life as well as an in-depth assessment of the morphometry of the intestinal mucosa.