饲料中不同脂肪水平对罗氏沼虾蚤状幼体生长、抗氧化、免疫和抗应激能力的影响

DIETARY LIPID LEVELS ON GROWTH, ANTIOXIDANT CAPACITY, IMMUNITY, AND STRESS RESISTANCE IN ZOEAE LARVAE OF MACROBRACHIUM ROSENBERGII

  • 摘要: 为探讨饲料中脂肪水平对罗氏沼虾(Macrobrachium rosenbergii)蚤状幼体生长、抗氧化、免疫和抗应激能力的影响, 研究将同一批罗氏沼虾亲体所产的蚤状幼体初体重为(0.19±0.05) mg随机分到养殖桶内, 试验共分为5组, 每组6个平行, 每个平行有5000尾幼体。试验第1周投喂丰年虫, 第2周开始投喂粗蛋白水平为52.25%, 脂肪水平分别为6%, 8%, 10%, 12%和14%的试验饲料, 饲养6周后, 进行全虾采样, 分析幼体的生长、抗氧化和免疫性能。同时, 将每个平行30尾后期幼体用于空气暴露试验, 分析幼体的抗应激能力。结果发现: 当饲料脂肪水平超过6%时, 幼体的存活率显著降低(P<0.05); 幼体变态率在脂肪水平为10%—12%时达到峰值, 显著高于其余各组(P<0.05); 幼体的末重、增重率及特定生长率呈现先上升后降低趋势, 在脂肪水平为12%时达到最大值(P<0.05)。幼体中C18:2n-6和n-6 HUFA的比例随饲料中相应脂肪酸比例的升高而显著升高, 脂肪水平为10%—14%组显著高于脂肪水平为6%—8%组(P<0.05); 幼体中C20:4n-6的比例随饲料中相应脂肪酸比例的降低而显著上升, 脂肪水平为8%—14%组显著高于脂肪水平为6%组; 幼体中DHA的比例随饲料中DHA比例的升高而呈降低趋势, 在脂肪水平高于12%时, 显著降低(P<0.05)。幼体的总抗氧化能力(T-AOC)活性在饲料脂肪水平为8%-10%时显著高于其余各组(P<0.05); 谷胱甘肽过氧化物酶(GSH-Px)活性在脂肪水平为10%时达到最高(P<0.05); 当脂肪水平为8%—12%时, SOD活性显著高于其余各组(P<0.05), 而丙二醛(MDA)含量在脂肪水平为10%—12%时显著低于其余各组(P<0.05)。饲料脂肪水平对幼体酸性磷酸酶(ACP)活性无显著影响, 但在脂肪水平为10%时幼体碱性磷酸酶(AKP)活性显著高于其余各组(P<0.05)。此外, 在饲料脂肪水平为12%时, 空气暴露试验后后期幼体的存活率显著高于6%、8%和14%脂肪水平组(P<0.05)。因此, 在实际生产中, 为了优化罗氏沼虾蚤状幼体的生长和健康状况, 建议将饲料的脂肪水平控制在10%—12%的范围内。

     

    Abstract: The availability of high-quality seedlings poses a significant constraint on the development of the aquaculture industry, and the dietary lipid levels are closely related to seedling development. To investigate the effects of dietary lipid levels on the growth, antioxidant capacity, immunity, and stress resistance of zoea larvae from the giant freshwater prawn (Macrobrachium rosenbergii), this experiment randomly assigned zoea larvae (initial body weight: 0.19±0.05 mg) produced by a single batch of M. rosenbergii broodstocks into aquaculture tanks. The study was divided into five groups, each comprising six replicates with 5000 larvae per replicate. During the first week, larvae were fed Artemia nauplii; from the second week onward, they received experimental diets containing crude protein at 52.25% but differing in lipid content-specially at levels of 6%, 8%, 10%, 12%, and 14%. After six weeks of feeding, whole-body samples were conducted to analyze the growth, antioxidant capacity, and immune performance of the larvae. Additionally, 30 post-larval prawns from each parallel were used for air exposure experiments to analyze stress resistance ability. The results showed that when the dietary lipid level exceeded 6%, the survival rate (SR) of the larvae significantly decreased (P<0.05); the metamorphosis rate peaking in the prawns fed a 10%—12% lipid-level diets, which was significantly higher than that of the other groups (P<0.05). The final weight, weight gain rate (WGR), and specific growth rate (SGR) first increased and then decreased, reaching a maximum at a lipid level of 12% diet (P<0.05). The proportions of C18:2n-6 and n-6 HUFA in larvae significantly increased with the elevation of the corresponding fatty acid proportions in the diet. The group with a lipid level of 10%-14% exhibited significantly higher proportions than the group with a lipid level of 6%—8% (P<0.05). Conversely, the proportion of C20:4n-6 in the larvae significantly increased as the corresponding fatty acid proportion in the diet decreased, with the groups having lipid levels of 8%-14% exhibiting significantly higher proportions than the group with a lipid level of 6%. The proportion of DHA in larvae exhibits a decreasing trend as the proportion of DHA in the diet increases, with a significant reduction observed when the lipid level exceeds 12%. (P<0.05). The total antioxidant capacity (T-AOC) activity of the larvae was significantly higher at dietary lipid levels of 8%—10% compared to the other groups (P<0.05). Glutathione peroxidase (GSH-Px) activity peaked at 10% group (P<0.05). SOD activity was significantly higher at lipid levels of 8%—12% than that in the other groups (P<0.05), while malondialdehyde (MDA) content was significantly lower at 10%—12% groups (P<0.05). Dietary lipid levels had no significant effect on acid phosphatase (ACP) activity, but alkaline phosphatase (AKP) activity was significantly higher in larvae fed 10% lipid-level diets compared to the other groups (P<0.05). Furthermore, in the air exposure experiments, the survival rate of the larvae was significantly higher at a dietary lipid level of 12% compared to the 6%, 8%, and 14% groups (P<0.05). Therefore, to optimize the growth and health status of M. rosenbergii zoea larvae in practical production, it is recommended to control the dietary lipid level within 10%—12%.

     

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