Fiber inclusion strategies in broiler diets: effects on performance, modulation of gut microbiota and sensory properties of meat

This study evaluated the effects of neutral detergent fiber (NDF) source and inclusion level on the performance, gut microbiota, and meat quality of slow-growing broilers. A total of 400 Naked Neck chicks were distributed across two experiments: initial (1–28 d) and growth/finishing (29–70 d). Birds were fed a control diet (CD) or diets containing an additional 3% or 6% NDF from wheat bran (WB) or guava residue (GR), resulting in the following treatments: CD, WB3%, WB6%, GR3%, and GR6%. In Experiment 1, birds fed WB3% and GR6% diets showed significantly lower body weight (BW) and weight gain (WG) compared to those fed CD (P < 0.05). Feed conversion ratio (FCR) was significantly higher (worse) in birds fed WB3%, WB6%, and GR6% diets relative to CD (P < 0.05), while no significant difference was observed between GR3% and CD (P > 0.05). Feed intake did not differ among treatments (P > 0.05). A significant interaction between NDF source and inclusion level was detected for BW, WG, and FCR (P < 0.05). In Experiment 2, no significant differences in performance traits were observed between CD and NDF-supplemented diets (P > 0.05). Carcass and meat cut yields were not affected by dietary treatments (P > 0.05). However, relative liver weight was significantly higher in birds fed guava residue-based diets (P < 0.05). Regarding sensory attributes, the GR6% diet promoted significantly higher scores for appearance and color (P < 0.05) and received the highest consumer preference. Microbiological analyses, although based on pooled samples, indicated a numerical trend toward lower thermotolerant coliform counts in NDF-supplemented groups. In conclusion, although NDF supplementation did not improve growth performance, the inclusion of 6% NDF from guava residue enhanced meat color and consumer preference, highlighting its potential as a functional ingredient for slow-growing broilers.