Effects of rosemary essential oil on growth performance and hematological parameters of young great sturgeon (Huso huso)

This study was conducted to investigate the immunological effects of rosemary (Rosmarinus officinalis) essential oil (RO) in young Beluga (Huso huso). Six groups (three replicates for each group) of 180 fish with initial weight of 130.94 +/- 5.28 g were feed with diets containing 0 (control), 0.01, 0.1, 1 and 2% of RO and a group of oxytetracycline (OT) (0.003%). Then they were randomly distributed to 18 tanks (ten fish per tank). Fish were acclimatized for two weeks and then fed with prepared diets based on 2% of their body weights per day for 8 weeks. At the end of the experiment, some immuno-hematological parameters, and serum metabolic products including cholesterol, glucose, total protein, albumin, globulin, triglyceride as well as some liver enzymes such as glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) were examined. Survival was not significantly different among all the treatments. Growth parameters remained unaffected at the end of the trial. However, the lowest BWI, SGR, and CF were observed in fish fed on 2% RO (P < .05). Significant improvements of the immune system and physiological condition were observed in young beluga fed on some levels of RO. Total protein and albumin were elevated significantly in OT group as well as all the groups fed with RO except for the one treated with 2% RO whereas glucose, liver enzymes and hemoglobin were decreased by using 0.01, 0.1, and 1% RO (P < .05). In conclusion, it can be suggested that rosemary essential oil can be used in the diet to improve hematological parameters and enhance the immunity of young beluga (Huso huso). Moreover it can be a suitable replacement for oxytetracycline in the diet of young beluga.