title: The probiotic Bacillus licheniformis ameliorates heat stress-induced impairment of egg production, gut morphology, and intestinal mucosal immunity in laying hens.
abstract: We investigated the effect of a 12-d exposure to 34°C plus dietary inclusion of the probiotic Bacillus licheniformis on the egg production, gut morphology, and intestinal mucosal immunity of laying hens. Ninety-six commercial hens (Hy-Line Brown) at the age of 60 wk were randomly allocated to 4 groups. After a period of laying rate adjustment (14 d), all the hens were subjected to 2 temperature treatments (12 d). Birds in 1 group were raised at 21°C and fed a basal diet, and birds in the other 3 groups were raised at 34°C and fed a basal diet supplemented with 0, 10(6), or 10(7) cfu of B. licheniformis per gram of feed, respectively. Rearing at 34°C depressed egg production and feed intake (P < 0.05). Compared with birds kept at 21°C, birds kept at 34°C had elevated serum levels of tumor necrosis factor-α (d 6), IL-1 (d 6 and 12), and corticosterone (d 6); decreased villus height (ileum: d 6; cecum: d 6 and 12) and ratio of villus height to crypt depth (ileum: d 6; cecum: d 6 and 12); fewer intraepithelial lymphocytes (ileum: d 6; cecum: d 6) and IgA-secreting cells (ileum: d 6; cecum: d 6 and 12); and more mast cells (ileum: d 6; cecum: d 6 and 12; P < 0.05). The number of goblet cells in the cecum increased at d 6 in heat-treated birds, and then deceased at d 12 (P < 0.05). Moreover, morphological examination showed injury to the villi of birds kept at 34°C. In general, inclusion of 10(7) cfu/g of B. licheniformis in the diet of heat-stressed hens was effective in overcoming the observed decline in egg production and feed intake, restoring the impaired villus structure, and sustaining a balanced mucosal immune response. Therefore, the probiotic B. licheniformis may be useful for ameliorating the adverse influence of heat on the egg production and gut health of laying hens.
authors.affiliation: State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
authors.forename: W
authors.initials: W
authors.lastname: Deng
authors.forename: X F
authors.initials: XF
authors.lastname: Dong
authors.forename: J M
authors.initials: JM
authors.lastname: Tong
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001407:Bacillus; D002645:Chickens / Q000276:immunology* / Q000382:microbiology*; D005260:Female; D041981:Gastrointestinal Tract / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D018869:Heat-Shock Response; D018928:Immunity, Mucosal / Q000276:immunology; D007070:Immunoglobulin A / Q000032:analysis; D007150:Immunohistochemistry / Q000662:veterinary; D007375:Interleukin-1 / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D010058:Oviposition / Q000276:immunology*; D019936:Probiotics / Q000494:pharmacology*; D011897:Random Allocation; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
chemical_list: D007070:Immunoglobulin A; D007375:Interleukin-1; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha