Multi-omics reveals that adding complex enzyme regulate gut microbiome and its metabolome thereby contributing to the improvement of immunity and reproductive performance of aged breeding layers

The production performance, organismal metabolism, physiological functions and digestive enzymes activities of aged layers decreased sharply and always be accompanied with intestinal damage and gut microbiota disorder. Exogenous addition of enzymes can improve the degradation of macromolecule nutrients and the activities of endogenous enzymes, which can enhance the production performance. Here, 224 Hy-Line Brown layers (55-weeks-old) were randomly allocated into basal diet (DC group) and 0.2g/kg multi-enzyme (protease, alpha-amylase, Pullulanase and glucoamylase) (CE group). The study was performed over 8 weeks. The CE diet significantly increased serum total protein [TP], globulin [GLB], immunoglobulin Y [IgY] and the antibody titers of Newcastle disease (ND) and H9 as well remarkably up-regulated total antioxidant capacity [T-AOC] while down-regulated aspartate aminotransferase [AST]. The CE diet significantly increased egg albumen height and haugh unit as well as the fertilization rate and hatching rate which represented reproductive performance of aged layers. Meanwhile, CE had a strong impact on the composition of ileum microbial which significantly enriched the genera Lactobacillus, Enterococcus and Faecalicoccus. CE enhanced the biodegradation based on metabolic functional of microbiota to multiple harmful substances and down-regulated the microbial functions related to sporulation and inflammation, thus enhancing the correlation between microbial communities. Furthermore, the metabolomic analysis indicated that the changes in metabolite patterns were closely related to changes in microbial communities. CE reduced the content of amino acids, while increased bile acids and derivatives and provided sufficient nutrients in the intestinal environment, resulting in reducing the autophagy and cell death of ileal epithelial cells together with promoting the growth of hindgut beneficial bacteria. In summary, CE can improve immunity and reproductive performance of aged layers, partly through regulating gut microbiota and its metabolites composition.