Abstract: Objective To study the correlation between the movement distance of small intestinal contents and survival time in female SD rat models after one-time satiation, and to evaluate its application value for postmortem interval estimation. Methods Adult female SD rats were randomly divided into postprandial groups （1, 2, 3, 4 and 5 h after feeding） and control group. The postprandial groups were fed for 1 h, meanwhile control group was kept fasting. All rats were sacrificed at the given time. The contents in stomach and small intestine were observed, described, compared and photographed, and the movement distance of small intestinal contents was measured. The data of postprandial groups were analysed by one-way analysis of variance. Results The stomach and duodenum of control group were empty with a little thin and yellow small intestinal liquid. The gastral cavities of 1 h postprandial group were full of undigested food. The evolutionary changes of character, colour and content were observed in the gastric and small intestinal contents of other postprandial groups. The movement distance of intestinal contents increased while the empty part decreased gradually. The differences among the postprandial groups were statistically significant （P<0.05）. Conclusion After a 24 h fasting with free drinking and the following 1 h feeding, an ideal animal model can be established successfully on female SD rats, which can provide an experimental basis for postmortem interval estimation based on the changes of small intestinal contents in forensic practice.

Key words: forensic pathology, models, animal, gastrointestinal contents, migration distance, postmortem interval, rats