Protective effect of dietary vitamin E and nano-selenium supplementations on growth performance and hematological parameters of rainbow trout (Oncorhynchus mykiss) exposed to sublethal level of ammonia

This study was performed to improve the physiological responses of rainbow trout to chronic stress of ammonia, as an inhibiting factor in recirculating aquaculture system, by using dietary antioxidant. 150 fish (initial mean weight of 8.4±0.84 g) were investigated in five treatments, each with three replicates for 60 days including fish fed with no supplemented food without ammonia exposure (C-), without supplemented food but with ammonia exposure (C+), with supplementation of vitamin E and ammonia exposure, with supplementation of nano-selenium and ammonia exposure (Se) and with supplementation of combined vitamin E and nano-selenium with ammonia exposure (E+Se). After 30 days of feeding with supplements, the fish were exposed to the ammonia (NH4OH: 0.2 ppm) for 30 days. Growth and hematological parameters were studied at days of 44 and 60. Results showed that feeding fishes with E+Se increased the growth parameters and reduced plasma ammonia compared to other treatments. Fish fed with E+Se had the highest RBC, hemoglobin and hematocrit levels while WBC was not significant compared to C- group. These results indicated the synergistic effects of dietary E+Se supplement in rainbow trout fish, it could compensate the imposed damaged by ammonia pollutions.