Astragalus polysaccharide improves the growth, meat quality, antioxidant capacity and bacterial resistance of Furong crucian carp (Furong carp♀ x red crucian carp♂)

To evaluate the functional effects of APS (Astragalus polysaccharide) on Furong crucian carp, APS-supplemented diets (0.00 %, 0.05 %, 0.10 % and 0.15 %) were prepared and utilized in feeding experiment. The results showed that the 0.05 % APS group has the highest weight gain rate and specific growth rate, and the lowest feed coefficient rate. In addition, 0.05 % APS supplement could improve muscle elasticity, adhesiveness and chewiness. Moreover, the 0.15 % APS group had the highest spleen-somatic index and the 0.05 % group had the maximum intestinal villus length. 0.05 % and 0.10 % APS addition significantly increased T-AOC and CAT activities while MDA contents decreased in all APS groups. The plasma TNF-& alpha; levels in all APS groups significantly increased (P<0.05), and the 0.05 % group showed the highest TNF-& alpha; level in spleen. In APS addition groups, the tlr8, lgp2 and mda5 gene expressions were significantly elevated, while xbp1, caspase-2 and caspase-9 expressions decreased in uninfected and A. hydrophila-infected fish. Finally, higher survival rate and slower disease outbreak rate were observed in APS-supplemented groups after being infected by A. hydrophila. In conclusion, Furong crucian carp fed by APS-supplemented diets possesses elevated weight gain rate and specific growth rate, and improved meat quality, immunity and disease resistance.

Automated summary

This study found that the addition of 0.05% APS had the best growth-promoting effects on Furong crucian carp, and improved muscle elasticity and chewiness. The 0.15% APS group had the highest spleen-somatic index, and the 0.05% group had the longest intestinal villus length. The addition of 0.05% and 0.10% APS significantly increased antioxidant capacity and decreased MDA content in the fish.