title: Effects of dietary Bacillus licheniformis on growth performance, immunological parameters, intestinal morphology and resistance of juvenile Nile tilapia (Oreochromis niloticus) to challenge infections.
abstract: The effects of oral administration of Bacillus licheniformis on growth performance, immunity, intestinal morphology and disease resistance of juvenile tilapia were investigated. Six experimental diets supplemented with different concentrations of B. licheniformis (0%, 0.02%, 0.04%, 0.06%, 0.08% and 0.1% of AlCare(®), containing live germ 2 × 10(10) CFU/g) were formulated, viz. control, T1, T2, T3, T4 and T5. Each diet was randomly assigned to triplicate groups of 30 fishes (3.83 ± 0.03 g). After 10 weeks of feeding trial, weight gain (WG), final body wet weight (FBW) and specific growth rate (SGR) increased significantly in groups T2, T3, T4 and T5 compared with control and T1 (p < 0.05). However, survival rate and feed conversion ratio (FCR) were not found to be significantly affected (P > 0.05). Compared with control, dietary B. licheniformis supplementation increased the content of complement C3 in serum significantly (P < 0.05). The lysozyme activity was observed to be highest in T2 (P < 0.05) without differences among other groups. However, SOD activity was not affected by B. licheniformis supplementation (P > 0.05). When tilapia were challenged against Streptococcus iniae, survival rate improved significantly when tilapia fed with T2, T3, T4 and T5 (P < 0.05). Although there was no significant differences in villi length and muscular layer thickness of anterior intestinal among the treatments, intestinal villi of fish fed with higher concentrations of B. licheniformis (T2, T3, T4, T5) tended to be regularly arranged and exhibited less exfoliation, twist and fusion. These results indicated that dietary supplementation of B. licheniformis not only increased the growth, immune response and disease resistance of juvenile tilapia, but also influenced anterior intestinal development and integrity. Furthermore, in our study, the optimal concentration of B. licheniformis in diets for tilapia was greater than or equal to 4.4 × 10(6) CFU/g.
authors.affiliation: Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China.
authors.forename: Biao
authors.initials: B
authors.lastname: Han
authors.affiliation: Department of Clinical Laboratory, The First Affiliated Hospital of Sun Yat-sen University, No. 58, Zhongshan Er Road, Guangzhou 510080, PR China.
authors.forename: Wei-Qing
authors.initials: WQ
authors.lastname: Long
authors.affiliation: Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China.
authors.forename: Ju-Yun
authors.initials: JY
authors.lastname: He
authors.affiliation: Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China.
authors.forename: Yong-Jian
authors.initials: YJ
authors.lastname: Liu
authors.affiliation: Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China.
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Si
authors.affiliation: Nutrition Laboratory, Institute of Aquatic Economic Animals, School of Life Science, Sun Yat-sen University, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, No. 135, Xin-gang Xi Road, Guangzhou 510275, PR China. Electronic address: lixiatian2002@163.com.
authors.forename: Li-Xia
authors.initials: LX
authors.lastname: Tian
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001407:Bacillus / Q000737:chemistry*; D023681:Cichlids / Q000254:growth & development; D004032:Diet / Q000662:veterinary; D060467:Disease Resistance; D005393:Fish Diseases / Q000188:drug therapy* / Q000276:immunology / Q000382:microbiology; D007113:Immunity, Innate / Q000187:drug effects; D007422:Intestines / Q000033:anatomy & histology / Q000187:drug effects; D019936:Probiotics / Q000008:administration & dosage / Q000494:pharmacology*; D013290:Streptococcal Infections / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000502:physiology*
keywords: Bacillus licheniformis; Growth; Immunity; Intestinal morphology; Oreochromis niloticus; Streptococcus iniae