Effects of diets containing dry extracts of Achillea millefolium, Mentha piperita and Echinacea purpurea on growth, hematological and immunological indices in juvenile common carp (Cyprinus carpio)

In this study, the effects of three herbal dry extracts (Achillea millefolium, Mentha piperita and Echinacea purpurea) were investigated on growth, hematological and immunological indices in juvenile common carp (Cyprinus carpio). 400 juvenile fish with initial weight of 14.30 ± 0.77g were studied in 10 treatment groups (9 treatment groups & a control) with four replicates for 60 days. Three levels (0.1, 0.5 and 1%) of dry extracts of each herb were prepared according to standard method and added to the commercial common carp feed. At the end of period twelve fish collected out of each group and the parameters were measured. In order to the results, weight gain, specific growth rate (SGR) and complement C4 were not affected by dietary treatments (P>0.05). Red blood cell (RBC) counts in 0.5 and 1%-diet groups as well as Hemoglobin in three levels of all herbs was increased (P≤0.05). Hematocrit in 0.5%, 1%-diet M. piperita and E. purpurea groups was shown significant increases (P≤0.05). Mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) in all groups except 0.1% M. piperita group and 0.5% E. purpurea were increased compare with control group (P≤0.05). MCHC in 0.5% E. purpurea and 0.1 and 1% M. piperita groups showed the highest values. Levels of 0.5% M. piperita and 1% E. purpurea and A. millefolium make significantly increases in total leukocytes and neutrophils (P≤0.05). Significantly increases of lymphocytes and decrease of monocytes were observed in levels of 0.5% E. purpurea and 1% level of all herbs groups(P≤0.05). Increased levels of immunoglobulin compared to control were significant only in 1% level of all herbs (P≤0.05). Complement C3 was also increased 1% of A. millefolium and M. piperita groups compared to the control (P≤0.05). All levels of A. millefolium and M. piperita and 1% E. purpurea groups caused a significant increase in lysozyme concentration compare with the control (P≤0.05).  The results indicated all three herb extracts in diet can improve immune responses and hematological parameters in common carp. Comparing these extracts, the M. piperita extract with a lower concentration is more efficient.