Effects of glucose oxidase combined with clostridium butyricum on broiler growth performance, nutrient digestibility, antioxidant function, intestinal barrier, and intestinal microbiota

In Experiment 1, a total of 300 one-day-old yellow-feathered broiler chicks randomly allocated to three groups, with 10 replicates per group and 10 birds per pen. The treatments included: (C1) control diet (basal); (G2 and G4) control diet supplemented with 2000 U/kg and 4000 U/kg of GOD. The results showed that, compared with C1 and G4, G2 significantly increased the final weight and ADG of broilers in the starter phase and resulted in the lowest feed conversion ratio (FCR) (P < 0.05). Based on the results of Experiment 1, Experiment 2 was conducted using 400 one-day-old yellow-feathered broiler chicks randomly allocated to four groups, with 10 replicates per group and 10 birds per pen. The treatments included: (C2) control diet (basal); (GO) control diet supplemented with GOD (2000 U/kg); (CB) control diet supplemented with CB (2 × 10⁸ CFU/kg); and (GC) a GOD + CB combination (at the aforementioned doses). Over the entire experimental period, the survival rate in the GO and the FCR in the CB were significantly improved compared with C2 (P < 0.05). Supplementation with GOD or CB alone significantly increased total phosphorus utilization and serum glutathione peroxidase activity compared with C2, and the combined supplementation of GOD + CB resulted in a significantly greater increase in superoxide dismutase activity than either additive alone (P < 0.05). Dietary CB supplementation increased the duodenal villus height-to-crypt depth ratio (V/C), whereas GOD supplementation increased jejunal V/C (P < 0.05). Furthermore, the GOD + CB combination induced a more pronounced upregulation of jejunal ZO-1 and Claudin-1 mRNA expression compared with individual supplementation (P < 0.05). Gut microbiota analysis showed that all treatment groups increased the relative abundance of Bacteroides and Akkermansia in the caecum. In conclusion, the combined supplementation of GOD and CB in broiler diets enhances intestinal digestion, promotes the proliferation of beneficial gut bacteria, improves intestinal health, and increases the apparent digestibility of nutrients, thereby ultimately improving broiler growth performance.