Investigation of immunostimulant effects of some non-forest products on rainbow trout (Oncorhynchus mykiss) culture

In the study, the immunostimulant effects of the methanolic extract of oyster mushroom and nettle and diseases resistance against Aeromonas hydrophila in rainbow trout were investigated. Two different concentrations of extracts were individually mixed with the basal diet and fed to rainbow trout for a four week period to assess the immunomodulatory characteristics of nettle and oyster mushroom. At the end of the study, rainbow trout was challenged with a strain of A. hydrophila. The study shows that final fish weight was higher in the experimental groups compared to control group (P<0.05) and no differences observed between oyster mushroom and nettle groups (P>0.05). Similar results were observed for groups SGR's. Both oyster mushroom and nettle groups FCR's were lower than control and the lowest one was % 1 oyster mushroom group. In the study all immune parameters were affected by dietary oyster mushroom and nettle extract intake (P<0.05). Nitroblue tetrazolium (NBT) activity was found higher in all experimental groups compared to control. Phagocytic activity was also determined higher in all experimental groups than control. However the highest level of phagocytic activity was observed in nettle groups. Lysozyme activity was higher in all experimental groups compared to control. However the highest level of lysozyme activity was observed in % 0.5 nettle group. Myeloperoxidase activity was investigated higer than control group but among the experimantal groups, nettle was found highest and no differences observed with respect to dosage. This study shows that the rainbow trout treated with % 0.1 kg-1 and % 0.5 kg-1 nettle extract when challenged with live A. hydrophila had the highest survival rate. No differences were exhibited between control and oyster mushroom group. According to study results, oyster mushroom and nettle is an effective non-specific immunostimulant for rainbow trout.