Effect of dietary prebiotic mannan oligosaccharide (mos) on growth performance, intestinal microflora, body composition, haematological and blood serum biochemical parameters of rainbow trout (oncorhynchus mykiss) juveniles

Abstract

The present study investigated the effects of prebiotic mannan oligosaccharide (MOS; activeMOS®) on the growth performance, intestinal microflora, body composition, haematological and serum biochemical parameters in rainbow trout juvenile (Oncorhynchus mykiss). After acclimation, fish (1.67±0.006 g) were allocated into 12 tanks (25 fish per tank) and triplicate groups were fed a control diet or diets containing 1, 2.5 and 4.0 g MOS kg -1. At the end of trial (60 days), blood samples were collected from caudal vein of 48 apparently healthy fish. Result showed that in level of 1 g MOS kg -1 acquired final weight, Body Weight Increase (BWI), Specific Growth Rate (SGR) and Feed Conversion Ratio (FCR) were significantly higher than the other experimental groups (p<0.05). The highest and the lowest growth performances were observed in 1 g MOS kgG1 and control, respectively. The fish fed with 1 g MOS kg -1 had highest but not significant (p<0.05) intestinal lactic acid bacterial count. By increasing the supplementation level of MOS, the content of crude protein increased (p<0.05). The result showed no significant differences in serum enzymes (ALT, AST, ALP) activity, glucose, cholesterol, triglyceride and total protein among treatments (p>0.05) but levels of lymphocyte in the group fed 1 g MOS kg -1 was significantly higher than other groups (p<0.05). Also, a non significant elevation of White Blood Cell (WBC), haematocrit, hemoglobin and eosinophil levels was found in the fish fed diet 1.0 g MOS kg -1 (p>0.05). The results indicated that dietary administration of mannan oligosaccharide at the level of 1 g kg -1 can positively influence the growth performance, intestinal microflora, body composition and some blood parameters of juvenile rainbow trout.