Ontogenetic development of intestinal digestive functions in White Pekin ducks

The ontogenetic development of intestinal digestive functions for avian species other than the domesticated chicken are not well documented. Therefore, this study was conducted to resolve the developmental patterns of some intestinal digestive functions in White Pekin ducks. The ducks were killed and their intestines harvested when they were 1, 3, 5 and 7 wk old. Several small intestinal tissue characteristics, sucrase and alkaline phosphatase (ALP) activities of homogenates from the small intestine mucosa were measured, and the small intestinal L-threonine uptake capacities were estimated with brush border membrane vesicles prepared from the corresponding age groups. Between 1 wk (0.37 +/- 0.04 kg) and 7 wk (3.79 +/- 0.06), posthatch ducks exhibited relative body growth rates of 352, 77 and 28% from 1 to 3, 3 to 5 and 5 to 7 wk, respectively. Allometric changes in small intestine weight indicated that the small intestine grew in direct proportion to the duck's metabolic body weight. Total homogenate sucrase activity per unit body weight did not differ (P > 0.05) among the age groups studied. Total homogenate ALP activity per body weight was lower at 3 wk than at 1 wk (P < 0.05) but did not differ (P > 0.05) among 3, 5 and 7 wk-old ducks. The development pattern of L-threonine uptake capacities normalized to body weights paralleled the course of relative body growth rates.