Effects of dietary medicinal herbs on growth performance, feed utilization and blood paramereters of sea bass (Dicentrarchus labrax L., 1758)

The study was conducted to investigate the effects of dietary thyme (Thymus vulgaris), rosemary (Rosmarinus officinalis) and fenugreek (Trigonella foenum graecum) supplementation in diet on growth performance, feed utilization, fillet composition, nitrogen excretion, biometric indexes, total liver fat and some blood parameters in sea bass (Dicentrarchus labrax). Three experimental diets were supplemented with medicinal herbs at 1%. After 45 days of the feeding trial, fish fed thyme diet had higher weight gain, and specific growth rate than other groups, had a lower feed conversion ratio and apparent lipid utilization than control group but not significantly changed (p>0.05). The addition of fish feed with thyme diet had a higher protein efficiency ratio, apparent protein utilization, apparent energy utilization, and fillet protein than control group (p<0.05). Fish fed thyme, rosemary and fenugreek diets had a lower nitrogen excretion (p>0.05), visceral fat index, hepatosomatic index, viscerosomatic index and total liver lipid than control group (p<0.05), bile somatic index and spleen somatic index levels had increased significantly (p<0.05). The medicinal herbs used in study did not significantly affect on the red blood cell count, hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration. However, white blood cell, neutrophil, monocyte counts, phagocytic activity, serum lysozyme and myeloperoxidase were enhanced and effected when compare to control group (p<0.05). Fish fed rosemary diets had a higher nitroblue tetrazolium than control group (p<0.05). In the fish groups fed with medicinal herbs had a higher superoxide dismutase activity than control group (p>0.05). Fish fed medicinal herb diets had significant decrease in the serum glucose, triglyceride, cholesterol, low density lipoprotein, very low density lipoprotein, alkaline phosphatase, glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, creatine kinase and lactate dehydrogenase levels (p<0.05). On the other hand the total protein, globulin, lipase and high density lipoprotein levels had increased (p<0.05). However, serum bilirubin, urea, uric acid, creatinine and electrolites were similar all the treatment groups (p>0.05).These results indicate that dietary supplementation of 1% thyme, rosemary and fenugreek in the commercial diets could improve some hematological, immunological, biochemical parameters and biometric indexes. In addition, suplemented thyme to the sea bass diet could improve feed utilization and fillet protein contents.