Effects of Bacillus subtilis ZY1 on production performance, egg quality, serum parameters and intestinal health in laying hens

To evaluate the effects of Bacillus subtilis ZY1 supplementation, production performance, egg quality, serum parameters, and intestinal health in laying hens were investigated. A total of 240 healthy 59-week-old Hy-Line Brown laying hens were randomly assigned to four groups: a control group (Con) fed a basal diet and three treatment groups supplemented with Bacillus subtilis ZY1 at levels of 0.05 % (LG), 0.1 % (MG), and 0.2 % (HG). The duration of trial lasted eleven weeks, including a one-week pre-feeding phase. The results indicated that dietary supplementation with ZY1 increased the egg laying rate in the LG and HG groups (P < 0.05) as well as improved the qualified egg rate in the LG and MG groups (P < 0.05). Moreover, the LG group also demonstrated superior egg quality and enhanced antioxidant capacity and immune function by decreasing the level of MDA (42.47 %) and improving the content of T-AOC, GSH-Px, CAT, SOD, IgM and IgG (34.31 %, 23.92 %, 37.68 %, 31.64 %, 14.01 %, and 17.84 %, respectively) in serum samples (P < 0.05). The changes in biochemical parameters such as AST, LDH, TG (12.40 %, 13.79 %, and 32.13 % decreased, respectively) and Ca (41.35 % increased) were particularly pronounced in LG groups (P < 0.05), indicating that ZY1 supplementation enhanced metabolic capacity of laying hens (P < 0.05). Furthermore, laying hens in the treatment groups exhibited significantly increased villus height (VH) and an elevated villus height-to-crypt depth ratio (VH/CD) within their duodenal tissues (P < 0.05). These findings suggest that dietary supplementation with ZY1 effectively improves production performance, egg quality, serum parameters, and intestinal health in laying hens; notably, a dosage of 0.05 % ZY1 was identified as the optimal level for these improvements. This study provides valuable insights into optimizing the application of Bacillus subtilis ZY1 in laying hen management practices.