Specific Pathogen-Free Rat Study

Specific Pathogen Free (SPF) Wistar rats weighing ~200–220 g were purchased from Liaoning Changsheng Biotechnology Co., Ltd. (Liaoning, China). (Note: due to the smaller spleen of germ-free rats compared to normal rats, it is not conducive to the study of SDD. Therefore, we chose to exclude Yersinia enterocolitica, dermatopathogenic fungi, and Klebsiella pneumoniae, and other pathogens SPF rats were studied.) The rats were raised in a SPF animal room with an independent ventilation system and standard temperature and humidity. All rats were fed using a standard 12–12 h light-dark cycle and allowed to adapt for 1 week prior to the study. The rats were provided with a standard diet (calorie composition: 65.5% carbohydrate, 10.3% fat, and 24.2% protein) and water. The experimental design was strictly in accordance with the principles and experimental requirements of the Animal Ethics Committee of Changchun University of Chinese Medicine (No. 2020317).