Abstract: 【Objective】To explore the effects of different feeding methods on the intestinal microbiota structure and serum immune indexes of Nanjiang yellow goat,this study aimed to offer insights for the optimal management and breeding practices of Nanjiang yellow goat.【Method】Thirty-two 3-month-old Nanjiang yellow goat,matched in body weight and health status,were randomly divided into 2 groups of 16 goats in each group,and subjected to either free-range grazing(FMGF) or enclosure feeding (SSGF).A pre-feeding period of 7 d was followed by a 60-day normal feeding period.On the 60^th d of the normal feeding period,6 Nanjiang yellow goat were randomly selected from each group,and rectal fecal samples were collected aseptically.Illumina HiSeq was used to analyze the variations in intestinal flora structure of Nanjiang yellow goat under different feeding methods.Blood samples were obtained from the jugular vein to detect serum immunoglobulins (IgA,IgG and IgM) and serum immune factors (IL-2,IL-4,IL-6 and TNF-α) using ELISA method.【Result】The IgM content in serum of FMGF group was significantly higher than that of the SSGF group (P<0.05,the same below),and the TNF-α content was significantly lower in SSGF group compared to the SSGF group.The Chao1 index of intestinal flora of Nanjiang yellow goat in FMGF group was significantly lower than that in SSGF group.At the phyla classification level,Firmicutes and Bacteroidota were identified as the dominant phylum in both the FMGF group and SSGF group.The relative abundances of Patescibacteria and Planctomycetota were extremely significantly higher in FMGF group compared to the SSGF group (P<0.01,the same below),whereas the relative abundances of Campylobacterota,Fusobacteriota and Fibrobacterota in FMGF group were significantly lower than those in SSGF group.At the level of genus classification,the dominant bacterial genera in FMGF group and SSGF group were Rikenellaceae_RC9_gut_group and the Christensenellaceae_R-7_group,respectively.The relative abundance of bacteria in FMGF group was found to be extremely significantly higher than that in the SSGF group,with genera such as Andidatus_Saccharimonas,Butyrivibrio,Anaeroplasma and Pseudobutyrivibrio.Conversely,the relative abundance of bacteria in the FMGF group was extremely significantly lower than that in the SSGF group,with genera such as Escherichia-Shigella,Akkermansia and Bacteroides.IgM content was extremely significantly negatively correlated with the relative abundance of Lactiplantibacillus,and was significantly negatively correlated with the relative abundance of Neisseria and Bacteroides.TNF-α content was extremely significantly negatively correlated with the relative abundance of Solobacterium and p-1088-a5_gut_group.【Conclusion】In comparison to house feeding,grazing can elevate IgM contents and reduce TNF-α contents in the serum of Nanjiang yellow goat.Additionally,grazing enhances the presence of beneficial bacteria,such as Errucmicrobiota and Desulfobacterota,in the intestinal tract,while simultaneously inhibiting the growth of harmful bacteria,such as Campylobacterota and Fusobacteriota.In conclusion,grazing has demonstrated substantial positive impacts on the immune function and intestinal beneficial microbiota composition of Nanjiang yellow goat.