The effects of some commercial probiotics as water additive on water quality, fish performance, blood biochemical parameters, expression of growth and immune-related genes, and histology of Nile tilapia (Oreochromis niloticus)

This study was performed to assess the effects of water addition of three brand names of probiotics on water quality, growth, feed utilization, carcass composition, blood biochemical parameters, histology, and Insulin-like growth factor 1 (IGF-1), growth hormone receptor (GHR), tumor necrosis factor alpha (TNF-alpha), and interleukin 1 beta (IL-1 beta) genes expression in juvenile O. niloticus. Four experimental groups were tested: T1, CG, control group without probiotics; T2, AquaStar (R) at 0.0015 g m(-3) day(-1); T3, EM (R) at 10 ml m(-3) day(-1); and T4, MicroPan (R) at 0.002 g m(-3) day(-1). Daily water change was 5%. Fish were fed 30% protein ALLER AQUA feed three times daily at 2.5% of body weight for 60 days. TAN and NH3 decreased significantly (p <= 0.05) in probiotics-treated groups, especially EM (R), compared with the control. Growth performance, fish biomass, and feed utilization increased significantly (p <= 0.05) in probiotics-treated groups, especially EM (R), compared with the control. A significant improvement of blood biochemical and immunity parameters (lysozyme and phagocytic activity) was observed in probiotics groups. The relative expression of IGF-1, GHR, TNF-alpha, and IL-1B genes in the liver, and spleen, significantly increased in groups EM (R) and AquaStar (R) equally (p <= 0.05) compared with the MicroPan (R) and control groups. The histological findings of gills, liver, spleen and intestine revealed healthier organs in AquaStar (R) and EM (R) groups than the other groups. This study confirms the importance of probiotics as a water additive to improve water quality, fish performance, blood biochemical, immunity, and up-regulating growth-related genes expression of Nile tilapia.