Effect of some herbal extracts on the health status of cultured Oreochromisniloticus

Abstract

Fish aquaculture has grown at an impressive rate over the past decades and a number of plant extracts were used to increase the resistance of fish by enhancing the non-specific defense mechanisms. Plants possess bioactive compounds including immunostimulants which are being more powerful than antibiotics and vaccines. So, this study was performed to determine the effect of onion, barley, rice extracts on growth, physiological, immunological parameters and antibacterial challenge with Areomonis hydrophila in Oreochromis niloticuls fish. • The study was carried on 210 fish randomly collected from private freshwater farm from Kafr Elshikh Governorate divided to equal 7groups /10 fish per group 3 replicates. • 30 apparently healthy fish selected for each concentration of plant extract. • 10 fish for pathogenicity test / group. The results of this study were as follow:- • Green onion leaves and barley seeds extracts have a growth promoting effect on tilapia fish where there is a significant increase in weight gain. • Rice straw extract doesn’t have any effect on fish growth. • Green onion leaves and barley seeds extracts have an immunostimulant effect on fish as there are significant increase in WBCs, globulin, phagocytic activity and lysozyme activity while rice doesn't affect the immunity with the highest results in onion. • There was non-significant changes in RBCs count and HB in all treated groupswhen compared with control one. • There was significant decrease in glucose level in fish fed on diet contain onion extract when compared with control one. • There were non-significant differences in ALT, AST and ALP level in all treated groups when compared with control one. • There was significant increase in total protein level due to increase globulins while there were non-significant differences in A/G ratio and Albumin. • There were non-significant changes in uric acid and creatinin level. • After the challenge test at the end of the experiment onion had the lowest mortality percent (20%), barley had moderate percent (30-40%) while rice had the highest percent as control group (70%). • The histopathological findings after challenge showed mild changes in onion groups and moderate changes in barley while rice groups have degenerative changes in liver, intestine, kidney and spleen.