Vol. 3, Issue 6, Part A (2018)

Author(s): Sameh Abd Elazeem Metwaly, MF Dowidar, Saad SS, Khater AM and Awad Somayah M

Abstract: This study evaluated the effect of probiotics on the growth performance, some immunological, biochemical and hematological parameters of Nile tilapia. Eight weeks feeding trials were conducted to examine the effect of three types of probiotics, multi-strain probiotics (6×10⁷ cfu/g), Bacillus subtilis (1×10¹¹ cfu/g) and Saccharomyces cerevisiae (2.6×10¹⁰ cfu/g) in commercial names Protexin, Biogen-S and Diamond V respectively. Nile tilapia (24±0.02 g) was fed probiotic-incorporated diets as well as control diet (free of probiotics) in triplicates. At 4th and 8th week of feeding trial, the growth performance of fish fed different probiotics was higher than those fed the control diet. No significant difference was observed among fish fed different probiotics for 4 or 8 weeks. Blood profile showed an increase in hemoglobin (Hb), red blood cell (RBCs), packed cell volume (PCV), total protein, and globulin while aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels decreased in fish fed different types of probiotics. Probiotics supplementation improved fish innate immunity based on lysozyme and respiratory burst activities over the control diet evaluated at 4th and 8th week. Likewise, significant up-regulation of the expression of cytokine genes, interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF α) estimated at 8th week by using quantitative RT-PCR were significantly higher than the control. After experimental period (8 weeks) fish from each group were challenged by pathogenic Aeromonas hydrophila (4×10⁸ cfu/ml) which exhibited better relative survival percentages than the controls. Dietary supplementation of probiotics improves growth performance, immune status and disease resistance in Nile tilapia. Also, the best results related to growth obtained from groups fed multi-strain probiotic.