Abstract
This study was aimed at evaluating the growth, hematology, immune-related genes, antioxidative status and resistance against heat stress (HS) in Nile tilapia fed diets with white button mushroom (WBM) at 0, 0.5, 1, 2, and 4% for 60 days. The final body weight, weight gain, specific growth rate, and feed intake were significantly increased quadratically by increasing the level of WBM in the tilapia diet (P < .05). However, the feed conversion ratio was quadratically decreased (P = .003). No significant alterations were found in the hematological variables due to WBM supplementation except for the Hb, RBCs, and WBCs which showed the highest values in 2% level (P < .05). Before HS, the glucose and cortisol levels were significantly decreased by increasing the level of WBM with the highest value in fish fed the control (P < .05). After HS, lower glucose values were displayed in fish fed WBM at 1 or 2% than the control, while cortisol was decreased in fish fed 0.5, 1, and 2%. The lysozyme activity was significantly increased in 1, 2 or 4% levels either before or after HS (P < .05), while phagocytic activity (PA) and phagocytic index (PI) increased by WBM in all levels before HS. Before HS, SOD and CAT were significantly increased in 1 and 2% levels (P < .05), while MDA was lowered by WBM at all levels. After HS, SOD was increased and MDA was decreased by WBM at 0.5, 1 or 2% levels, while CAT and GPx were increased by 1 and 2% levels (P < .05). The relative expression of INF-γ, TNF-α, and IL-1β genes showed increased transcription by WBM at 2% either before or after HS (P < .05). However, HSP70 was decreased by supplementing WBM at 0.5 to 4% levels either before or after HS (P < .05). Based on the measured parameters, the requirement of dietary WBM for Nile tilapia is 2.15 to 2.75%. To conclude, WBM is recommended to cope with the impacts of heat stress on Nile tilapia aquaculture by improving the growth, antioxidative resistance, and immunity.
•White button mushroom (WBM) improved the growth performance of Nile tilapia.•Fish reared under heat stress and fed WBM had better antioxidative status than fish fed the control diet.•WBM improved the immunity of Nile tilapia to cope with the impacts of heat stress.•WBM increased the transcription of INF-γ, TNF-α, and IL-1β, and downregulated HSP70 genes.•Based on the measured parameters, the requirement of dietary WBM for Nile tilapia is 2.15 to 2.75%.