Efficacy of vitamin E with or without probiotic, astaxanthin or rosemary extract on growth performance, survival, haematological parameters, antioxidant activity and liver enzymes in rainbow trout (Oncorhynchus mykiss)

Growth and health status of rainbow trout (Oncorhynchus mykiss) (170.46 ± 1.16 g) fed diets containing 50 mg kg−1 vitamin E (control), 250 mg kg−1 vitamin E, 500 mg kg−1 probiotic (Bacillus lichiniformis + Bacillus subtilis each at 108 cfu g−1), 50 mg kg−1 astaxanthin and 500 mg kg−1 rosemary (Rosmarinus officinalis) extract were assessed for 4 months. No significant differences were seen in growth performance among treatments and between treatments and control (p > 0.05). The highest values of protein and lipid efficiency ratios were observed in 250 mg vitamin E, astaxanthin and rosemary trails. Probiotic trail demonstrated lower activity of liver superoxide dismutase (p