Abstract:The aim of this study was to study the effect of dietary β-glucan on certain growth and blood physiological indices of the rainbow trout (Oncorhynchus mykiss). The experimental animals were robust, with similar weight of (450±50) g. The control group was fed basal feed, and the experimental groups were fed basal feed supplemented with β-glucan at three concentrations: 0.05%, 0.1%, and 0.2%, three replicate tanks for each group. After 30 days of feeding, the weight gain rate (WGR) in the 0.2% β-glucan group was the highest, significantly higher than that of the other groups (P<0.05). Meanwhile, the WGR of the 0.05% β-glucan group was the lowest. The specific growth rate (SGR) of the 0.2% β-glucan group was significantly higher than that of the other groups (P<0.05). No significant differences in SGR were found among the 0.05% and 0.1% β-glucan groups and the control group (P>0.05). The hepatosomatic index (HSI) of the 0.2% β-glucan group was the highest, significantly higher than that of the other groups (P<0.05). The condition factor (CF) of the 0.2% β-glucan group was significantly lower than that of the other groups (P<0.05). After 30 days of feeding, the number of leukocytes and erythrocytes and the plasma hemoglobin concentration were significantly higher in the experimental groups than in the control group (P<0.05). The number of leukocytes in the 0.05% β-glucan group, which was not significantly different from that of the 0.1% β-glucan group (P>0.05), was significantly higher than that of the 0.2% β-glucan group and control group (P<0.05). The number of erythrocytes in the 0.1% β-glucan group was the highest, significantly higher than that in the other groups (P < 0.05). Furthermore, the number of erythrocytes in the β-glucan groups was significantly higher than that of the control group (P<0.05). The changes in hemoglobin concentrations were consistent with changes in erythrocyte count. In conclusion, dietary β-glucan can improve the growth performance and favorably change the blood physiology indicators of rainbow trout, with the appropriate concentration of β-glucan being 0.2%.
