Dietary mixed Bacillus strains promoted the growth indices, enzymatic profile, intestinal immunity, and liver and intestinal histomorphology of Nile tilapia, Oreochromis niloticus

In the current investigation, a 4-week feeding trial was carried out to study the special effects of the dietary probiotic, Sanolife® PRO-F (a combination of Bacillus subtilis 3.25 × 109 CFU/g, Bacillus licheniformis 3.50 × 109 CFU/g, and Bacillus pumilus 3.25 × 109 CFU/g) supplementation on growth performance, serum biochemical immune parameters, intestinal digestive enzymes activities, antioxidants assay, and the expression of pro-inflammatory cytokines and antioxidant-related genes with a specific reference to intestinal histomorphometry of Nile tilapia, Oreochromis niloticus, which fed with Sanolife® PRO-F at 0 (B0), 0.5 (B0.5) and 1 (B1) g kg−1 diet, respectively. At the end of the feeding trial, the achieved results revealed that Bacillus strains probiotic supplementation significantly improved the growth performance including final body weight (FBW), weight gain (WG), specific growth rate (SGR), and feed utilization when matched to the control group (p < 0.05). Concerning serum biochemical parameters, there was a significant reduction in the serum cholesterol and triglyceride levels in fish-fed Bacillus strains (p < 0.01). Serum lysozyme activity showed greater values in the case of the B0.5 and B1 groups (p < 0.01) compared with the control. No changes were estimated in the levels of glucose, hepatic (alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and renal biomarkers (Urea, Creatinine, and Uric acid) in the serum of fish-fed B0.5 and B1 diets. Additionally, the specific activities of protease, amylase, and lipase enzymes were significantly increased upon Bacillus strains՚s incorporation in O. niloticus diets. As well, the antioxidant capacity of catalase (CAT) and superoxide dismutase (SOD) enzymes in the liver and spleen were significantly increased with diminished malondialdehyde (MDA) levels. Correspondingly, the mRNA expression of the antioxidant glutathione peroxidase (GPx) enzyme in the intestinal tissue was notably increased in the control group. The length of intestinal villi, absorptive epithelium, and goblet cell counts were greater in O. niloticus fed on Bacillus strains diets. Given the obtained results, the dietary supplementation of Sanolife® PRO-F to Nile tilapia, O. niloticus at 0.5 g kg 1 and 1 g kg−1 diet can recover the growth, feed utilization, and health condition with the safety of Sanolife® PRO-F probiotic supplementation on liver and kidney function.