Effects of dietary garlic (Allium sativum) extract on survival rate, blood and immune parameters changes and disease resistance of Common carp (Cyprinus carpio carpio Linnaeus, 1758) against Spring Viremia of Carp (SVC)

This study evaluated the influence of dietary garlic (Allium sativum) extract onsurvival rate and changes in blood and immune parameters of Common carp (Cyprinus carpio), fed with two different concentrations of aqueous garlic extract after exposure to spring viremia of carp virus (SVCV). The experiments have executed in two steps: Firstly, 270 fingerlings of Common carp with an average weight of 15±3.4 g have cultivated in 18 aquaria with 15 liters of water. Fish were fed with 1 and 5 g garlic extract kg^-1 basal diet for 8 weeks. In the second step, 240 fingerlings have been randomly divided into 8 groups (A: negative control; B: virus control; C and D: extract controls and E-H: treatment groups) with 3 replicates in each group include of 10 fish in each replicate, and the fish have been exposed to SVCV for 4 weeks. The mortality rate, blood and immune parameters and virus isolation have been determined at the end of experiments. The results have showed that the survival rate of the Common carp fed with 1 and 5 g garlic extract kg^-1 basal diet (E-H groups) had a significant increase compared to the control groups (p<0.05) and RBC, hemoglobin, hematocrit, MCH, MCHC had Significant increase compared to the virus control group (B) (p<0.05). WBC in groups D, E, F and G in comparison to control group A and B and lymphocyte in groups D, E and F compared to control group B had a Significant increase (p<0.05). Also, the Common carp fed with two concentrations of garlic extract increased lysozyme and IgM in groups C-H compared to group A (p<0.05). Finally, cell culture and RT-PCR have been applied for detection of SVC virus from fish samples. The results have been indicated that addition of garlic extract (Especially 5 g kg^-1) in fish dietary has led to a higher immunity and survival rate of common carp exposed to SVCV.