嗜吡啶红球菌发酵黄芪对石斑鱼生长性能、消化、免疫和抗氧化指标的影响OA

The experiment aimed to investigate the effects of dietary supplementation with Rhodococcus pyridinivorans fermented Astragalus on the growth performance,immune function,digestive enzyme activities,and antioxidant indicators of pearl gentian grouper.A total of 360 pearl gentian groupers with a body weight of(9.56±1.14)g were selected and randomly divided into four groups,with three replicates per group,and 30 fish per replicate.The control group was fed a basal diet,while groups T1,T2 were fed the basal diet supplemented with 1%Astragalus powder,1%Rhodococcus pyridinivorans fermented Astragalus powder,respectively.The feed in group T3 was sprayed with 1%Rhodococcus pyridinivorans cell suspension.After the standard rearing period,the fish were challenged with 1×108 CFU/mL of Vibrio harveyi for 10 days,with the injection volume being 1%of the fish's body weight.The preliminary trial lasted seven days,followed by 28 days of standard rearing and a 10-day challenge test period.The results showed that the weight gain rate and specific growth rate in the group T2 were significantly higher than those in the group T3 and the control group(P<0.05),while the feed coefficient was significantly lower than that in the other groups(P<0.05).The hepatic activities of acid phosphatase(ACP)and alkaline phosphatase(AKP),as well as muscle lysozyme(LZM)activity in the groups T1 and T2 were significantly higher than those in the other groups(P<0.05).The serum activities of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)in the group T2 were significantly lower than those in the group T3(P<0.05).The intestinal activities of lipase,pepsin,trypsin,and α-amylase in the group T2 were significantly higher than those in the other groups(P<0.05).The hepatic peroxidase(POD)activity,total antioxidant capacity(T-AOC),catalase(CAT)activity,and glutathione(GSH)content in the groups T1 and T2 were significantly higher than those in the other groups(P<0.05),while the muscle malondialdehyde(MDA)content in the group T2 was significantly lower than that in the other groups(P<0.05).The challenge test results showed that the survival rate in the group T2 reached 100.00%,and the hepatic non-specific immune and antioxidant indicators were significantly better than those in the other groups(P<0.05).The study shows that dietary supplementation with Rhodococcus fermented Astragalus can effectively enhance the immune function,digestive enzyme activities,and antioxidant capacity of pearl gentian grouper,promote healthy growth,and strengthen their resistance against Vibrio harveyi infection.