Effect of dietary prebiotic mannan oligosaccharide and β-1,3 glucan on growth performance, body
composition and immunity response of rainbow trout (Oncorhynchus mykiss) were investigated for a
six week culture period. Four feeding strategies were set, including feeding prebiotic-free diet
continuously (control), feeding dietary prebiotic continuously (T1), feeding dietary alternately (one
week prebiotic+one week control diet) (T2) and 2 Day prebiotic+5 Day control diet (T3). The
experiment carried out in 500 liters Plastic tanks. 32 juveniles rainbow trout with initially average
weight 19.6 ± 0.06 were stocked in tanks and fed up a day. The results showed no significance
difference was observed on growth performance and feeding indexs (P>0. 05). There was significant
differences in composition carcass (P<0. 05). The highest protein content was observed in the control
treatment and maximum fat was observed in treatment 2. There were significant differences in the
serum lysozyme activity (P<0.05). Continuous administration of prebiotic mannan oligosaccharide and
β-1,3-glucan showed significantly higher serum lysozyme activity (53.89) than those in the control
group (16.88).The result indicated that continuously applying mannan oligosaccharide and β-1,3-
glucan into the diet compare to discontinuous administration caused improved growth performance
and immunity response for rainbow trout.