Functional role of Atractylodes macrocephala polysaccharide in mitigating the effects of reduced-fishmeal and low-protein diets in Litopenaeus vannamei

This study evaluated Atractylodes macrocephala polysaccharides (AMP) supplementation in reduced-fishmeal (LF) and low-protein (LP) diets for Litopenaeus vannamei . Five diets were formulated: (1) control (25 % FM, 42 % protein); (2) LF + 0.03 %A (20 % FM + 0.03 % AMP); (3) LF + 0.05 %A (20 % FM + 0.05 % AMP); (4) LP + 0.03 %A (39 % protein + 0.03 % AMP); (5) LP + 0.05 %A (39 % protein + 0.05 % AMP). The results showed that L. vannamei fed the control diet showed a significantly lower weight gain and specific growth rate compared to those fed diets with LF + 0.05 %A, LP + 0.03 %A and the LP + 0.05 %A, AMP supplementation increased PWG by 1.90–13.42 % compared with the control diet ( P < 0.05). No differences were observed in survival rate, feed efficiency, composition in whole shrimp and muscle, or hemolymph biochemical indices ( P > 0.05). The enzyme activity of antioxidant indicators in control group such as glutathione peroxidase, superoxide dismutase, and total antioxidant capacity activities in hepatopancreas and intestine were lower compared with AMP groups, but higher malondialdehyde levels compared with AMP groups ( P < 0.05). It also showed the lowest enzyme activities of control group of total nitric oxide synthase, glutamic oxaloacetic transaminase, acid phosphatase, glutamic pyruvic transaminase, alkaline phosphatase in hemolymph compared with AMP groups, plus reduced intestinal acid phosphatase and alkaline phosphatase compared with AMP groups ( P < 0.05). Antioxidant-related genes ( gpx, cat, po, Mnsod, Cusod ) and immune-related genes ( akp, toll, imd, alf, hsp70 ) in hepatopancreas and intestine were downregulated in controls versus other diets ( P < 0.05). Overall, Dietary 0.03–0.05 % AMP effectively mitigated adverse effects of reduced FM and protein, enhancing growth, antioxidant immune capacity. • A. macrocephala polysaccharides (AMP) enhanced growth in L. vannamei fed a low fish meal & reduced protein diet. • AMP boosted antioxidant capacity in L. vannamei under a low fish meal & reduced protein diet. • AMP strengthened non-specific immunity in L. vannamei fed a low fish meal & reduced protein diet.