Effects of dietary Supplemental thyme essence (Thymus vulgaris L.) on growth, hematological and serum biochemical parameters of Rainbow trout Oncorhynchus mykiss (Walbaum, 1792)

This study was carried out to investigate the effects of different levels of thyme (Thymus vulgaris L.) essential oil on growth performance, hematological and serum parameters of Rainbow trout (Oncorhynchus mykiss). For this purpose, 4 treatments including 0 (control), 250, 500 and 750 mg thyme essential oil/kg diet were provided. 156 rainbow trout an average initial weight 69.38±0.44 gr were divided randomly in each treatment (with 3 replicates). At the end of 48 days, growth related parameters, hematological and biochemical parameters were measured. Results showed that growth related parameters including final weight, weight gain, weight gain percent, feed conversion ratio and specific growth rate had no significant differences among treatments (p>0.05). Dietary supplemented of Thyme essential oil had no significant influence on Hemoglobin, hematocrit and red blood cell compared to control (p>0.05). White blood cell showed significant difference compared to control, as the highest level of white blood cell was observed in 500 mg thyme essential oil/kg diet (p0.05). Serum lysozyme content showed significant difference between thyme treatments and control group and the highest level of lysozyme was obtained in treatment supplemented with 750 mg thyme essential oil/kg diet (p