Abstract

This study was conducted to evaluate the impacts of a probiotic-enzyme complex (PEC) on laying performance, egg quality, intestinal health, and serum metabolite levels in laying hens fed a low-protein diet. A total of 720 Hy-Line Brown laying hens aged 45 weeks were randomly allocated into three groups, with six replicates per group and 40 hens per replicate. The experiment lasted for 10 weeks. The high-protein (HP, 17% CP) group was fed a high-protein diet, whereas the low-protein (LP, 15% CP) group received a low-protein diet, and the PEC group was fed the same LP diet supplemented with the 0.1% PEC (consisting of Bacillus subtilis K104, Lactobacillus plantarum A490, Clostridium butyricum DS142, and acid protease). Results indicated that the PEC group exhibited significantly higher egg production rate and average daily egg yield compared to the LP group (p < 0.05), while the FCR was significantly lower than that of the LP group (p < 0.05). The eggshell strength, jejunal villus height, and villus height-to-crypt depth ratio in the PEC group were significantly higher than those in the LP group (p < 0.05). Additionally, the probiotic-enzyme complex enhanced the biosynthesis of arginine and cofactor pathway in laying hens, increasing the relative abundance of beneficial bacteria such as Lactobacillus and Bacillus. In conclusion, supplementing laying hen diets with the probiotic-enzyme complex improves gut health and metabolic function, thereby enhancing laying performance and eggshell quality, and mitigating the adverse effects of low-protein diets in laying hens.