Yafei Duan,Yun Wang,Jiasong Zhang,Yongxu Sun,Jun Wang
Organic acids acts as an growth promoter and antimicrobial agent in aquaculture. The present study investigated the effects of a natural organic acid - succinic acid (SA) on the growth, digestive enzymes , immune response and resistance to ammonia stress of Litopenaeus vannamei . The shrimps were firstly fed with diets containing different levels of SA: 0% (Control), 0.25% (SA1), 0.50% (SA2), and 1.0% (SA3) ( w / w ) for 56 days, followed by an acute ammonia stress for 48 h. The results indicated that dietary of SA improved the growth of shrimp, and increased the survival rate of shrimp after ammonia stress for 48 h. The amylase , lipase and pepsin activity increased in hepatopancreas in three SA group, while trypsin activity was only increased in the SA1 and SA2 groups. At 56 d, T-NOS activity, proPO and HSP70 gene expression level increased in the three SA group, PO activity increased in the SA1 and SA2 groups, T-AOC content and Toll gene expression level increased in the SA2 and SA3 groups, Trx and SOD gene expression level increased in the SA2 group, while Imd , GS and GDH gene expression level was no changes. After exposure to ammonia stress for 48 h, immune biochemical parameters (T-AOC and PO) and genes ( proPO , HSP70 , Trx and GDH ) expression level increased in the three SA group, T-NOS activity, Toll , Imd and GS gene expression level increased in the SA2 and SA3 groups, while SOD gene expression level increased in the SA1 and SA2 groups. These results indicated that SA improved growth, enhanced digestive and immune capacities of L. vannamei against ammonia stress, and may be a potential feed additive for shrimp. The optimal dietary supplementation dosage is 0.50% ( w / w ) in diet.
Shi-Wei Xie,Li-Xia Tian,Yu-Ming Li,Weiwen Zhou,Shuai-Lin Zeng,Hui-Jun Yang,Yong-Jian Liu
An 8-week feeding trial was conducted to evaluate the effect of proline on anti-oxidative capacity, immune response and stress tolerance of juvenile Pacific white shrimp , Litopenaeus vannamei . Six practical low fishmeal diets (15% fishmeal) were formulated to contain graded levels (2.02, 2.14, 2.27, 2.38, 2.49, 2.6%) of l -proline. Each diet was randomly assigned to triplicate groups of 30 shrimps (approximately 0.41 g) and the shrimps were fed 4 times a day to apparent satiation. Growth performance was not affected by proline levels (P > 0.05). But higher levels of proline increased hydroxyproline content in the whole body (P = 0.004). And survival after 60 h acute NH 3 stress increased with the increasing dietary proline levels (P = 0.015). High levels of proline also increased the proline oxidase (POX), nitric oxide (NO), total antioxidant capacity (T-AOC) and phenoloxidase (PO) activities in hemolymph or hepatopancreas after the 60 h NH 3 stress compared to basic group which had lowest proline level. Broken-line analysis showed that the optimal dietary proline requirement of L. vannamei was 2.29%, 2.32% and 2.34% based on PO, POX and 60 h survival after NH 3 stress. These results clearly indicated that 2.29–2.34% of proline in the low fish meal diet could improve anti-oxidative capacity, immune response, NH 3 stress tolerance of L. vannamei , and proline may be a conditionally essential AA for L. vannamei . Statement of relevance This study indicates that proline may be a conditional amino acid for white shrimp under the environment stress, especially when fed with low fish meal diet. The results will contribute to the low fish meal diet study of the white shrimp.
危险品化学品经营许可证（带存储）