This study assessed the impact of dietary supplementation of single and multi-strain Bacillus -based probiotics on growth performance, intestinal morphometry, blood parameters, immune-oxidative status, and transcriptomic response of Nile tilapia for 60 days.
Fish (N=150, 1.632±0.035g) were allocated into five experimental groups: 1) Control group (CG) that was fed on a basal diet; 2) Eco. 0.01%, received basal diet with 0.1 g Kg-1 Ecobiol; 3) Eco. 0.02%, received basal diet with 0.2 g Kg-1 Ecobiol ; 4) Pro-F FMC 0.001%, received basal diet with 0.001 g Kg-1 Sanolife PRO-F FMC ; 5) Pro-F FMC 0.002%, received basal diet with 0.002 g Kg-1 Pro-F-FMC.
Fish received Pro-F FMC 0.002% displayed higher growth performance than CG (P < 0.05) while Pro-F FMC 0.001% exhibited the highest intestinal weight. Sanolife PRO-F FMC supplementation improved intestinal villi length and goblet cell number while decreased inter villi space (P < 0.05). The best hemoglobin, hematocrit, and monocyte percent were observed in Pro-F FMC 0.001% whereas Pro-F FMC 0.002% revealed the best leukocyte, lymphocyte, and neutrophil contents. Pro-F FMC supplemented groups showed better phagocytic activity, phagocytic index, and lysozyme activity than Ecobiol supplemented groups and CG. Pro-F FMC 0.001% enrichment induced the highest up-regulation level of NPYα , AgRp-2 , ghrelin and GH-1 whereas Pro-F FMC 0.002% significantly upregulated IGF-1 and IGF-2 gene expression. Eco.0.02% induced the highest up-regulation level of Orexin and Galanin gene expression.
Conclusively, dietary enrichment with single or multi strain Bacillus -based probiotics is likely to improve growth, immunological parameters and transcriptomic response of Nile tilapia.