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    高温下蛋白质水平对凡纳滨对虾生长、饲料利用与能量代谢的影响

    DIETARY PROTEIN LEVELS ON GROWTH PERFORMANCE, FEED UTILIZATION, AND ENERGY METABOLISM OF LITOPENAEUS VANNAMEI UNDER HIGH TEMPERATURE STRESS

    • 摘要: 为了探究高温条件下饲料蛋白水平对凡纳滨对虾(Litopenaeus vannamei)生长、饲料利用及能量代谢的影响, 研究配制蛋白水平分别为40%、42.5%和45%的三种配合饲料(P40、P42.5、P45)。挑选初始体重为(5.42±0.01) g的凡纳滨对虾, 在32℃水温下开展为期8周的养殖试验。结果显示: P42.5组对虾增重率和特定生长率显著高于P40和P45组, 饲料系数显著降低(P<0.05)。血淋巴生化指标显示, P42.5组白蛋白含量和超氧化物歧化酶(SOD)活性均最高, 而P45组血氨水平最高。抗氧化指标显示, P42.5组肝胰腺溶菌酶(LZM)、过氧化氢酶(CAT)等酶活性均达到最大值; 与另两组相比, P45组丙二醛(MDA)含量显著升高(P<0.05)。肠道健康方面, P42.5组肠绒毛高度及紧密连接蛋白基因(Claudin-3、Occludin、ZO-1)表达量均最高。在蛋白质合成方面, P42.5组翻译起始因子基因(eIF3K、eIF4E)表达量最高, P40组表达最低。能量代谢方面, TCA循环相关酶基因表达(IDHMDHCS)和代谢产物含量均在P45组达到最高。在32℃水温下, 蛋白水平为42.5%的饲料可有效促进对虾生长, 增强抗氧化能力与肠道屏障功能, 并维持蛋白质合成及能量代谢平衡; 40%的蛋白质水平抑制了对虾能量代谢过程并导致生长性能下降; 蛋白水平过高(45%)导致氧化应激加剧、肠道屏障损伤及生长性能下降。因此, 合理调控饲料蛋白水平是提升凡纳滨对虾高温养殖稳定性、营养利用效率及健康水平的重要途径。

       

      Abstract: To investigate the effects of dietary protein levels on growth, feed utilization, and energy metabolism of Pacific white shrimp (Litopenaeus vannamei) under high-temperature conditions. Three practical diets containing 40%, 42.5%, and 45% crude protein were formulated and designated as the P40, P42.5, and P45 groups, respectively. Juvenile Pacific white shrimp with an initial body weight of (5.42±0.01) g were cultured at 32℃ for an 8-week feeding trial. The results showed that the weight gain rate and specific growth rate of shrimp in the P42.5 group were significantly higher than those in the P40 and P45 groups, while the feed conversion ratio was significantly decreased (P<0.05). Hemolymph biochemical analysis indicated that the P42.5 group had the highest albumin content and superoxide dismutase (SOD) activity, whereas the P45 group exhibited the highest hemolymph ammonia level. For hepatopancreatic antioxidant indices, the activities of lysozyme (LZM), catalase (CAT), and other related enzymes reached their maximum values in the P42.5 group. Compared with the other two groups, malondialdehyde (MDA) content in the P45 group was significantly increased (P<0.05). Regarding intestinal health, the P42.5 group showed the highest intestinal villus height and mRNA expression levels of tight junction protein genes (Claudin-3, Occludin and ZO-1). In terms of protein synthesis, the transcript levels of translation initiation factor genes (eIF3K and eIF4E) were the highest in P42.5 group and the lowest in P40 group. For energy metabolism, the expression levels of key enzyme genes related to the TCA cycle (IDH, MDH, and CS) and the concentrations of corresponding metabolites peaked in the P45 group. Under the rearing temperature of 32℃, a dietary protein level of 42.5% effectively promoted shrimp growth, enhanced antioxidant capacity and intestinal barrier function, and maintained the homeostasis of protein synthesis and energy metabolism. A dietary protein level of 40% suppressed energy metabolism and resulted in reduced growth performance. In contrast, excessive dietary protein (45%) aggravated oxidative stress, impaired intestinal barrier integrity and led to the decline of growth performance in Pacific white shrimp. Therefore, reasonable regulation of dietary protein supply is an important approach to improve the culture stability, nutrient utilization efficiency and health status of Pacific white shrimp under high temperature conditions.

       

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