immunomodulatory effect of allium sativum and echinacea purpurea to increase resistance of rainbow trout against yersinia ruckeri

Some plants have antibacterial properties and enhance the immune system of fish. the objective of this study was to investigate the effect of allium sativum and echinacea purpurea extract on immune responses and resistance oncorhynchus mykiss to yersinia ruckeri. for this purpose, 1050 fishes (50 ± 5.6 g) were distributed in seven groups (with three replication) and fed with supplemented commercial diet for 30 days as follow: commercial diet without plant extract (control), 0.5% and 1% a. sativum, 0.5% and 1% e. purpurea, a combination of 0.5% a. sativum and 0.5% e. purpurea, and a combination of 1% a. sativum and 1% e. purpurea. after treating period all groups were fed with commercial diet to next 15 days. on 0, 15, 30 and 45 days, blood and serum samples were prepared to measure lysozyme, and total immunoglobulin. a bacterial challenge were conducted to investigate resistance of treated fishes against y. ruckeri on day 30. the results showed that a. sativum 1% enhanced immune parameters on days 15 and 30 beside control group significantly. also this difference was significant for total immunoglobulin on 45th day. a. sativum 1% caused to decrease cumulative mortality of fishes after bacterial challenge significantly. based on the results a. sativum extract %1 stimulated the immune system and increased resistance of rainbow trout against y. ruckeri.