Effect of various levels of dietary prebiotic mannan oligosaccharide on haematological and some blood serum biochemical parameters of cultured juvenile Rainbow trout (Oncorhynchus mykiss)

The aim of this study was to evaluate the effect of mannan oligosaccharide (MOS; activeMOS®) on haematological and biochemical parameters of Rainbow trout (Oncorhynchus mykiss) juveniles. Fish fed during 60 days with a basal diet supplemented with 1، 2. 5 and 4 g/kg g kg-1 MOS. Blood samples were collected from caudal vein of 36 apparently healthy fish at the end of trial and Data was analysed by regression analysis and pearson correlation test. There were no significant differences in serum enzymes activity between treatments (P>0. 05). There were no differences in the glucose، cholesterol، triglyceride، uric acid، total protein and bilirobine between treatments (P>0. 05). but the level of WBC significantly higher in the group fed 1g/kg g kg-1 MOS than other groups (P<0. 05). A non significant elevation of haematocrit، haemoglobin level and lymphocyte was found in the fish fed diet 1 g/kg g kg-1mannan oligosaccharide (P>0. 05). The results indicate that dietary administration of mannan oligosaccharide at the level of 1 g/kg g kg-1 can positively influence on some blood parameters of juvenile rainbow trout.