Determination of immunostimulant effects of green olive tree (Phillyrea latifolia) in rainbow trout (Oncorhynchus mykiss) immune system

Medicinal plants have beentaken into consideration with their growth promotor, antioxidant and immunostimulant activities as feed additive in recent years. With this purposes, in the present study, the effects of green olive tree (Phillyrea latifolia) aqueous methanolic extract non-specific immune responses,haematological parameters, on growth performance and antioxidant enzyme activity in rainbow trout were investigated.Fish with an average initial weight 41.71 ± 1.08 g,were divided into 7 groups (Control (0%), leave 0.1% (PLY0.1), leave 0.5% (PLY0.5), leave 1% (PLY1), fruit 0.1% (PLM0.1), fruit 0.5% (PLM0.5), fruit 1% (PLM1)) in 21net cages (1.5m X 1.5m X 1.5m) with stocking density of 40 fish/net cage (triplicate net cage were assigned for each experimental group). To determine immune and haematological responses, on 15th, 45th and 75th day of the study, superoxide anion production (SAP), lysozyme (LYS), myeloperoxidase activity (MPO), red blood cells (RBC) count, haemoglobin content (Hb), haematocrit value (Hct) and red blood cells indices including; the mean cell volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC) were examined respectively.At the end of the study to determine growth performance, weight gain (WG), specific growth rate (SGR) and feed conversion ratio (FCR), to determine antioxidant activity, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and lipid peroxidation level (LPO) were analysed. 15th day of the study, SAP results were found higher in all experimental groups compared to control (P<0.05). The highest SAP was determined on PLM0.1 and PLM1 groups (P<0.05). 75th day of the study, SAP was significantly decreased in PLY0.1 and PLY0.5 groups. LYS activity was elevated in all experimental groups compared to control (P<0.05) except PLY0.5 group (P>0.05) on 75th day of the study. Increased MPO activity was determined 45th day of the study in all experimental groups compared to control (P<0.05). haematological results showed an increase in almost all experimental group on any sampling time compared to control. At the end of the study, the results showed that final weight, WG and SBO of the PLY 0.5 and PLM 0.5 groups were higher than the control and other experimental groups (P <0.05). FCR was significantly increased on PLY0.1, PLM0.1, PLM0.5 and PLM1 groups compared to control. No differences were observed on PLY0.1 and PLY0.5 group compared with the control (P>0.05). SOD activity was decreased in PLY1, PLM0.1 and PLM0.5 groups compared to control (P<0.05). Other group's SOD activity showed no differences (P>0.05). CAT was decreased in PLY0.1 and PLM0.1 groups compared to control. There is not any significant differences wereobserved between control and PLM0.5 group. PLY0.1, PLY1 and PLM1 groups' CAT activity was increased compare to control (P<0.05). GPx as increased in all PLM groups and also PLY groups compared to control. All these study results showed that both PLY0.5 and PLM0.5 have growth promoter effects. PLY0.5 also come forward with its FCR value. From the study results, it n also conclude that leaves and fruits have immunostimulant and antioxidant activity. As a conclusion green olive tree (Phillyrea latifolia) aqueous methanolic extract can be used as a feed additive in O. mykiss diet