Effects of a Compound Probiotic on Production Performance, Intestinal Health, Immune Function, and Gut Microbiota in Broiler Chickens

Maintaining intestinal health is fundamental to immune competence and disease resistance in broiler chickens; however, effective nutritional strategies that enhance gut barrier integrity and systemic health remain under investigation. This study evaluated the effects of a multi-strain probiotic composed of <i>Lactobacillus buchneri</i>, <i>Lactobacillus casei</i>, <i>Lactobacillus fermentum</i>, <i>Lactiplantibacillus plantarum</i>, and <i>Bacillus subtilis</i> on growth performance, meat quality, immune response, antioxidant capacity, and intestinal health in broilers. The research included 144 Ross 308 broilers aged one day, distributed randomly into two diet groups, each containing 6 replicates of 12 birds. During the 42 d trial, the control group (CON) was fed a basal diet composed of corn and soybean meal, with the compound probiotics (CP) diet additionally containing 0.3% compound microbial preparation. Growth performance, meat quality, serum immune and antioxidant indices, intestinal morphology, intestinal barrier-related genes and cecal microbiota were analyzed. Compared with the CON, CP supplementation significantly increased average daily gain, reduced feed conversion ratio, and improved eviscerated and breast muscle yields (<i>p</i> < 0.05). Meat quality was enhanced, as indicated by higher pH_45min, increased redness (a*), and reduced shear force and drip loss in breast muscle (<i>p</i> < 0.05). In addition, CP broilers exhibited improved amino acid and fatty acid profiles in breast muscle (<i>p</i> < 0.05). Serum analysis revealed elevated immunoglobulin G and interleukin-10 levels, reduced pro-inflammatory cytokines, and enhanced antioxidant capacity in the CP group (<i>p</i> < 0.05). Probiotic supplementation significantly improved intestinal morphology and upregulated barrier-related genes such as mucin-1 (<i>MUC-1</i>), claudin-1(<i>CLDN-1</i>), zonula occludens-1 (<i>ZO-1</i>), and occludin (<i>OCLN</i>) (<i>p</i> < 0.05). Moreover, cecal microbiota analysis demonstrated increased abundance of Bacteroidota and enrichment of beneficial genera, including <i>Megamonas</i>, <i>Ruminococcus</i>, and <i>Prevotella</i> (<i>p</i> < 0.05). Overall, dietary supplementation with 0.3% compound probiotics effectively enhanced growth performance, immune function, antioxidant capacity, and intestinal health in broilers.