Diets Containing Defatted Black Soldier Fly Larvae Meal Improve Intestinal Morphology and Antioxidant Capacity in Wenchang Chickens

Background/Objectives: This study evaluated the effects of dietary defatted black soldier fly (Hermetia illucens) larvae meal (DBSFLM) as a partial replacement of traditional dietary protein sources on growth performance, carcass traits, meat quality, serum biochemical and antioxidant-related parameters, ileal morphology, and cecal microbiota in Wenchang chickens. Methods: Ninety healthy 55-day-old male chickens were randomly assigned to three dietary treatments with six replicates of five birds each: a basal diet without DBSFLM (H0), or diets containing 3% (H3) or 5% (H5) DBSFLM for 26 days. Results: Average daily feed intake, average daily gain, and feed conversion ratio did not differ significantly among treatments (p > 0.05). Abdominal fat percentage was higher in H5 than in H0 (p < 0.05), whereas other measured carcass traits were unaffected. No significant differences were observed in the measured meat quality parameters, including pH, drip loss, cooking yield, shear force, and meat color (p > 0.05). Dietary DBSFLM increased serum glutathione peroxidase activity and decreased malondialdehyde concentration, while serum creatinine concentration decreased in both DBSFLM groups (p < 0.05). DBSFLM also decreased ileal crypt depth and increased the villus height-to-crypt depth ratio (p < 0.05). Changes in the relative abundances of Firmicutes_A, Proteobacteria, Akkermansia, Butyricicoccaceae, and Agathobaculum were observed in cecal microbiota. Conclusions: Overall, partial replacement of traditional dietary protein sources with 3–5% DBSFLM was associated with changes in selected serum parameters, ileal morphology, and cecal microbial composition, without significant differences in growth performance or most measured meat quality traits.