Effects of dietary orange fiber supplementation on growth performance, plasma biochemical parameters, abdominal fat deposition, volatile fatty acid concentration, and cecal microbiota in 817 broilers

Orange fiber (OGF), a byproduct of citrus juice processing, is characterized by high soluble dietary fiber and various bioactive compounds that may positively affect nutrient metabolism and intestinal health. This study investigated the effects of dietary OGF supplementation on growth performance, plasma biochemical indices, abdominal fat deposition, volatile fatty acid (VFA) concentrations, and cecal microbiota composition in 817 broilers. A total of 192 one-day-old birds were randomly assigned to four dietary treatments containing 0%, 2%, 4%, or 6% OGF, each with six replicates of eight birds. During days 22-49, broilers fed 6% OGF exhibited significantly higher body weight and average daily gain (ADG), while the feed-to-gain ratio (F/G) was significantly reduced in the 4% and 6% OGF groups compared with the control (P < 0.05). Consistently, over the entire experimental period (1-49 d), ADG remained significantly higher in the 6% OGF group, and F/G was significantly lower in the 4% and 6% OGF groups (P < 0.05). Plasma analysis revealed that 6% OGF increased triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) levels but reduced blood glucose (BG). Birds in the 6% OGF group also had greater abdominal fat weight (AFW) and abdominal fat percentage (AFP). Cecal fermentation analysis showed significantly elevated concentrations of acetic acid, propionic acid, and butyric acid in the 6% OGF group (P < 0.05). Sequencing results indicated higher microbial diversity (Shannon and Pielou indices) and distinct community clustering in the OGF group. OGF increased the relative abundance of Bacillota, Faecalibacterium, Alistipes and the Christensenellaceae R-7 group while decreasing Bacteroidota, Actinomycetota, Bacteroides, Prevotellaceae UCG-001 and Olsenella. These findings demonstrate that 6% OGF enhances growth performance, modulates lipid and glucose metabolism, promotes beneficial microbial communities, and increases VFA production in broilers, providing evidence for its use as a sustainable functional ingredient in poultry feed.