Abstract: 【Objective】 This study was aimed to investigate the effects of yeast peptide on immune function,digestive and metabolic performance and intestinal microorganisms of Sichuan White geese. 【Method】 A total of 120 healthy Sichuan White geese at 1 day of age with equal amount of male and female,were randomly divided into 2 groups,with 6 replicates in each group and 10 geese in each replicate.Geese in control group were fed a basal diet,geese in experimental group were supplemented with 200 mg/kg of yeast peptide on top of the basal diet.Geese had access to feed and water ad libitum in the 70 d of the experiment period.At the end of the test,jugular blood was collected to determine IgA,IgM,IgG contents and lysozyme activity,and spleen,thymus,bursa of Fabricius,liver,pancreas,muscularis propria,glandularis propria,duodenum,jejunum and ileum were collected to determine the immune function,digestive performance,intestinal morphology and microorganisms of the geese. 【Result】 Compared with control group,① IgM content and lysozyme activity in serum,splenic index and bursa of Fabricius index of geese in yeast peptide group were significantly increased (P＜0.05);② The liver index, ileum index,and duodenum length of geese in yeast peptide group were significantly increased (P＜0.05),but there was no significant effect on digestive enzymes activity and the length of jejunum and ileum of geese (P＞0.05);③The villus height,V/C and mucosal layer thickness of duodenum and ileum of geese in yeast peptide group were significantly increased (P＜0.05),while the mucosal layer thickness of jejunum and crypt depth of ileum were significantly lower (P＜0.05);④ The relative abundance of Proteobacteria, Parasutterella, Clostridium_ⅩⅣb, Sutterella,Sporobacter,Pseudoflavonifractor and Roseburia in intestines of geese in yeast peptide group were significantly increased (P＜0.05).The LEfSe analysis results showed that compared with control group,the abundance of Sutterellaceae,Burkholderiales,Betaproteobacteria,Helicobacteraceae,Campylobacterales and Epsilonproteobacteria were significantly increased in yeast peptide group (P<0.05). 【Conclusion】 The addition of 200 mg/kg of yeast peptide to the feed under the conditions of the present study improved the immune function and digestive performance of geese to a certain extent,as well as improved the intestinal microbial composition and promoted intestinal health.

Key words: Sichuan White geese; yeast peptide; immune function; intestinal microorganisms