Effects of dietary fermented sweet potato residue on growth performance and cecal microbiota in sichuan white geese during the finisher period (28 to 70 days of age)

This study aimed to evaluate the potential of fermented sweet potato residue (FSPR) as a partial substitute for corn in goose diets, determine its optimal inclusion level, and assess its effects on intestinal morphology, immune status, and cecal microbiota. A 42-day feeding trial was conducted with 144 twenty-eight-day-old male Sichuan white geese randomly assigned to one of four dietary treatments: a corn-soybean meal basal diet (CON) and three test diets replacing corn with 5%, 8%, or 12% of the corn with FSPR on a dry matter basis. Growth performance, carcass traits, meat quality, serum biochemistry, intestinal morphology, and cecal microbiota were comprehensively assessed. Dietary FSPR inclusion induced a significant, dose-dependent reduction in average daily feed intake (P < 0.001). However, feed conversion ratio was linearly improved (P < 0.001), which compensated for the reduced intake and sustained growth performance. Despite reduced intake, the 8% FSPR group achieved the highest final body weight, and the feed conversion ratio was significantly improved in the 8% and 12% FSPR groups (P < 0.001). Additionally, FSPR improved meat quality by maintaining higher postmortem thigh muscle pH. Systemically, supplementation enhanced immunoglobulins (IgM, IgG) and anti-inflammatory IL-10 without inducing pro-inflammatory markers. Ileal morphology was optimized, evidenced by a significantly increased villus height-to-crypt depth ratio (P < 0.001). Cecal microbiota analysis revealed that FSPR enriched beneficial taxa (e.g., Phocaeicola, Lachnospiraceae), enhanced microbial diversity, and upregulated metabolic pathways for carbohydrate and amino acid biosynthesis. In conclusion, FSPR effectively replaces corn in goose diets, enhancing feed efficiency, meat quality, and immunity, likely associated with through gut microbiota modulation, with 8% identified as the optimal inclusion level.