Effects of dietary Shirazi thyme (Zataria multiflora Boiss) and vitamin E on growth and biochemical parameters in common carp (Cyprinus carpio)

Using of phytobiotics as fish feed additives have been interestingly increased during the recent decade. The aim of the current study was to evaluate the effect of individual and combined level of thyme and vitamin E in common carp. Juveniles were separately fed by four distinct diets including control (commercial diet without any additive), supplemented with 1% ground Shirazi thyme, supplemented with 100 mg/kg vitamin E and a mixture of Shirazi thyme and vitamin E (TE) with mentioned concentrations for 45 days. Sampling was done at 15, 30 and 45 days after feeding trial duration and some growth and plasma biochemical parameters were evaluated. The individual thyme supplementation significantly increased weight gain (%), feed conversion efficiency and decreased feed conversion ratio (P<0.05). Plasma enzymes (AST, ALT, ALP and LDH) were not affected in all experimental groups. Comparing to the control, triglyceride and glucose were significantly elevated in TE complex at all sampling times. Plasma proteins (total protein, albumin and globulin), cholesterol and creatinine were not altered in all treatments. In conclusion, dietary supplementation with individual 1% Shirazi thyme had not any harmful effects on plasma biochemical parameters and increased growth performance of the fish. Moreover, positive effects of thyme on fish growth were more than vitamin E. Supplementation by a mixture of vitamin E and thyme also displayed no priority than individual using of Shirazi thyme in the diet.