Effects of Partial Replacement of the Basal Diet with Fermented Bamboo Powder on Growth Performance, Abdominal Fat Deposition, and Antioxidant Capacity in Yellow-Feathered Broilers

Bamboo is an abundant plant resource with potential for use as an unconventional feed ingredient; however, its application in animal production remains relatively limited. This study aimed to evaluate the effects of partially replacing the basal diet with fermented bamboo powder (FBP) on the growth performance, slaughter traits, meat quality, serum biochemical parameters, antioxidant status, immune-related parameters, and intestinal digestive enzyme activities of yellow-feathered broilers. Two-year-old bamboo was used as the raw material and subjected to microbial fermentation for 14 d, followed by drying and sieving to obtain FBP. A total of 480 one-day-old yellow-feathered broilers were randomly assigned to four dietary treatment groups, with six replicate cages per treatment and 20 birds per cage. The control group received a basal diet, whereas the experimental groups received diets in which 0.5%, 1.0%, or 1.5% of the basal diet was replaced with FBP. The feeding trial lasted 56 d. During the starter phase, dietary FBP replacement significantly increased final body weight and average daily gain (ADG). During the grower phase, final body weight and ADG increased with increasing FBP inclusion levels. Over the entire experimental period, the overall treatment effect on ADG was not statistically significant, whereas dietary replacement with 1.0% and 1.5% FBP significantly reduced the feed-to-gain ratio (F/G) (p < 0.05). FBP replacement also significantly reduced abdominal fat percentage and increased breast muscle redness (a*) at 24 h postmortem (p < 0.05). Serum triglyceride (TG) and total cholesterol (TC) concentrations decreased, whereas high-density lipoprotein cholesterol (HDL-C) concentrations increased in FBP-fed broilers (p < 0.05). Regarding antioxidant and immune-related parameters, FBP significantly affected catalase (CAT) activity, total superoxide dismutase (T-SOD) activity, and total antioxidant capacity (T-AOC) (p < 0.05). CAT activity was highest in the 1.0% FBP group, whereas serum immunoglobulin A (IgA) concentrations were significantly higher in the 1.0% and 1.5% FBP groups than in the control group (p < 0.05); the 0.5% group did not differ significantly from the control. No significant effects were observed on organ indices or intestinal digestive enzyme activities (p > 0.05). In conclusion, partial replacement of the basal diet with FBP improved feed conversion efficiency and was associated with reduced abdominal fat deposition and favorable changes in selected serum lipid, antioxidant, and immune-related parameters. Although phase-specific improvements in growth performance were observed, overall ADG did not differ significantly among dietary treatments. These findings suggest that FBP has potential as a partial substitute for conventional feed ingredients in yellow-feathered broiler diets. Further studies are needed to confirm these effects and establish the optimal inclusion level under different production conditions.