Use of dietary rosemary ( Rosmarinus officinalis L.) extract as a growth promotor and immunostimulant in common carp

This study aimed to investigate the effects of rosemary leaf extract (Rosmarinus officinalis L.) on growth, haematological parameters, immunological profile and body composition in common carp (20.35 ± 0.37 g). The fish (n = 240) were fed with 0.0%, 0.25%, 0.5% and 1% of rosemary extract in 12 aquaria (300 L) with three replicates (each with 30 fish) for 60 days. At the end of the trial, final weight, WG, SGR, FCR and CF levels were significantly higher in a dose-dependent manner in the groups fed the diet containing rosemary extract compared with the control group. Moreover, the results of measured trial indices showed a significant increase in a dose-dependent manner in WBC and RBC counts, haemoglobin, haematocrit, lysozyme, complement, respiratory burst, total protein, albumin and glucose in the fish fed the diet containing rosemary extracts compared with the control group. The contents of cholesterol, triglyceride and LDL were significantly decreased in a dose-dependent manner and HDL level significantly increased in the groups fed diets containing rosemary extract. The findings of this research suggest that adding rosemary extract, especially 1%, to the food regime could positively change the growth parameters, haematological and immunological profiles of Cyprinus carpio.