Effect of Astragali Radix on growth, immunity and related gene expression of Whitmania pigra

Abstract

To explore the effect and mechanism of Astragali Radix on growth and immunity of Whitmania pigra, 0, 0.01%, 0.03%, 0.05%, 0.07%, 0.09% of Astragali Radix were added to the daily feeding of Wh. pigra. After 60 days of feeding, the growth performance, activities of digestive enzyme and anti-reverse enzyme, inner quality, the expression levels of GH, IGF-1 and digestive enzyme-related genes were measured. Meanwhile, the effects of heat stress on the living conditions of Wh. pigra were observed and counted, and the expression levels of HSP70 and immune related genes were measured. The results showed that the final weight, weight gain rate, specific growth rate, activities of digestive enzyme and anti-reverse enzyme, the expression levels of GH, IGF-1 and digestive enzyme-related genes in the Astragali Radix group were higher than those in the control group, and with the increase of Astragali Radix concentration, the above-mentioned indexes increased initially and then decreased, and significantly higher in the 0.05% of Astragali Radix group than in the other groups (P<0.05). There was no significant difference in the inner quality of Wh. pigra between the Astragali Radix and control groups. The survival rate of Wh. pigra was negatively correlated with heat stress treatment duration. With the prolongation of heat stress treatment duration, the expression levels of HSP70 and immune related genes were increased first and then decreased, and peaked at 24 h. The survival rate and the expression levels of HSP70 and immune related genes in the Astragali Radix group were higher than those in the control group, and was significantly higher in the 0.05% of Astragali Radix group than in the other groups (P<0.05). In conclusion, Astragali Radix can increase the activities of digestive enzyme and anti-reverse enzyme, the expression levels of related genes, growth performance, and immunity to heat stress of Wh. pigra. It is suggested to add 0.05% of Astragali Radix in the actual production of Wh. pigra to improve the production profit.