Bacillus velezensis, Inulin and their Synbiotic Combination Improve Productive and Reproductive Performance and Gut Health via Microbiota Modulation in Breeding Geese

The Wanxi White Goose (Anser cygnoides) is an important genetic resource and economic asset valued for its hardiness and local adaptability, but to maximize their health and production capacities, more sustainable and effective management strategies than the traditional feeding methods are required.A total of 180 geese were randomly assigned and divided into six groups and fed, based on dietary inclusion: control feed group, B. velezensis level one group, B. velezensis level two group, inulin level one group, inulin level two group, and a synbiotic group (e.g., combining B. velezensis level one and inulin level one).Geese were humanely slaughtered by trained personnel after the feeding trial, blood, tissues, and cecal content were collected to evaluate the physiological parameters.Synbiotic group showed significantly higher (P<0.05)productive and reproductive performance traits, followed by the B. velezensis level two group.Reproductive hormone analysis revealed significant (P<0.05)increase in prolactin, luteinizing hormone, and follicular stimulating hormone, with the SYN group showing the highest levels.Histomorphometric analysis revealed significant (P<0.05)differences in intestinal morphology among the treatment groups, including changes in villus height, crypt depth, and other intestinal structural parameters.The gene related to tight junctions, like Occludin, Claudins1 and TJP1 were upregulated in the duodenum jejunum and ileum and exhibited the upregulated expression trend across the treated groups.The microbiota dynamics and short chain fatty acids production in treated groups showed a higher abundance of the family-level taxa Bacteroidaceae and Prevotellaceae, while Peptococcaceae was more abundant in the control group.These findings demonstrate that combination of B. velezensis and inulin positively influences the performance-gut-metabolite axis in Wanxi White breeding geese.