A four-week feeding trial, followed by a challenge test, was conducted to evaluate the effects of Lactococcus lactis and astaxanthin on the growth performance, digestive ability, antioxidant capacity, immunity, and disease resistance of Litopenaeus vannamei against Vibrio alginolyticus. Specifically, shrimp were randomly allocated into 12 tanks (100 shrimp per tank), and divided into 4 groups with 3 replicates. Shrimp were fed on either a control (CK) or three other treatment diets by supplementing L. lactis at 1 × 10⁸ CFU g⁻¹ diet (L), astaxanthin at 250 mg kg⁻¹ diet (A) and L. lactis at 1 × 10⁸ CFU g⁻¹ diet combined with astaxanthin 250 mg kg⁻¹ diet (LA). Results indicated that treatment diets significantly improved growth performance and increased the activity of digestive enzymes relative to the control diet. Particularly, the highest parameters were recorded in shrimp fed on astaxanthin alone. Moreover, statistical analysis revealed significant differences in antioxidant and immune enzymes activities between shrimp in the CK and A groups. From the results of the challenge test, shrimp fed on treatment diets all had significantly lower mortality as compared to the control diet, and shrimp fed on astaxanthin alone had the lowest mortality. Dietary supplementation of astaxanthin alone significantly increased the relative expression of Cru, Pen-3α, SOD and LZM and decreased the relative expression of proPO in the gut of shrimp as compared to the control diet. The results indicates that the relative expression levels of most selected immune-related genes were significantly up-regulated in shrimp fed on astaxanthin alone, which may explain the best disease resistance observed in this group. Taken together, the findings of this study suggest that astaxanthin can positively affect the growth performance, digestive ability, antioxidant capacity, immunity, and disease resistance of L. vannamei against V. alginolyticus. Notably, these effects are superior to those induced by L. lactis alone or in combination with L. lactis.

进行了为期 4 周的喂养试验，随后进行了挑战试验，以评估乳酸乳球菌和虾青素对南美白对虾生长性能、消化能力、抗氧化能力、免疫力和抗溶藻弧菌抗病能力的影响。具体而言，将虾随机分配到12个池中（每池100只虾），分为4组，3个重复。通过添加1 × 10 ⁸ CFU g ^{-1日粮 (L) 的乳酸乳}球菌、250 mg kg ^-1日粮 (A) 的虾青素和乳球菌1 × 10 ⁸ CFU 克^-1饮食结合虾青素 250 mg kg ^-1饮食（洛杉矶）。结果表明，与对照日粮相比，处理日粮显着改善了生长性能并增加了消化酶的活性。特别是，仅用虾青素喂养的虾的参数最高。此外，统计分析显示CK和A组虾的抗氧化和免疫酶活性存在显着差异。从攻击试验的结果来看，与对照饮食相比，饲喂处理饲料的虾的死亡率均显着降低，仅饲喂虾青素的虾死亡率最低。与对照饮食相比，单独添加虾青素可显着增加虾肠道中 Cru、Pen-3α、SOD 和 LZM 的相对表达，并降低 proPO 的相对表达。结果表明，大多数选定的免疫相关基因的相对表达水平在仅用虾青素喂养的虾中显着上调，这可能解释了在该组中观察到的最佳抗病性。综上所述，本研究结果表明，虾青素可以对虾的生长性能、消化能力、抗氧化能力、免疫力和抗病能力产生积极影响。南美白对虾对抗溶藻弧菌。值得注意的是，这些效果优于单独由乳酸乳球菌或与乳酸乳球菌联合诱导的效果。