Alimentary Circulation in the Pup During the Postnatal Period

The intramural alimentary tract circulation of 21 normal newborn, 2-, 5-, and 14-day-old pups was studied by the radiorubidium fractionation technique. The weight of the esophagus, stomach, small intestine, and colon increased threefold to sevenfold over a two-week period following birth, while the animals' body weight increased by only 50%. Total esophageal and gastric flow remained unchanged, while small intestinal flow exclusive of the distal ileum reached a maximum at 2 days of age. The mean percentage of cardiac output and mean percentage of cardiac output per gram remained significantly higher in the jejunum than in the ileum through the first two weeks of life. The flow rate to the duodenum was significantly higher than the jejunum for the first two days of life.