Shao Ming, Xu Hao, Ge Xianping, Zhu Jian, Huang Dongyu, Ren Mingchun, Liang Hualiang
Wuxi Fisheries College, Nanjing Agricultural University, Wuxi214081, People's Republic of China.
Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center (FFRC), Chinese Academy of Fishery Sciences (CAFS), Wuxi214081, People's Republic of China.
Br J Nutr. 2022 Jun 8:1-12. doi: 10.1017/S0007114522001763.
This 62-d research aimed to evaluate the effects of dietary lysine levels (DLL) and salinity on growth performance and nutrition metabolism of genetically improved farmed tilapia (GIFT) juveniles (). Six diets with lysine supplementation (1·34, 1·70, 2·03, 2·41, 2·72 and 3·04 % of DM) were formulated under different cultured salinities in a two-factorial design. The results indicated that supplemental lysine improved the specific growth rate (SGR) and weight gain (WG) and decreased the feed conversion ratio (FCR). Meanwhile, the fish had higher SGR and WG and lower FCR at 8 ‰ salinity. Except for moisture, the whole-body protein, lipid and ash content of GIFT were increased by 8 ‰ salinity, which showed that DLL (1·34 %) increased the whole-body fat content and DLL (2·41 %) increased whole-body protein content. Appropriate DLL up-regulated mRNA levels of protein metabolism-related genes such as target of rapamycin, 4EBP-1 and S6 kinase 1. However, 0 ‰ salinity reduced these protein metabolism-related genes mRNA levels, while proper DLL could improve glycolysis and gluconeogenesis mRNA levels but decrease lipogenesis-related genes mRNA levels in liver. 0 ‰ salinity improved GLUT2, glucokinase and G6 Pase mRNA levels; however, sterol regulatory element-binding protein 1 and fatty acid synthase mRNA levels were higher at 8 ‰ salinity. Moreover, 8 ‰ salinity also increased plasma total protein and cholesterol levels and decreased glucose levels. These results indicated that the recommended range of lysine requirement under different salinity was 2·03-2·20 % (0 ‰) and 2·20-2·41 % (8 ‰) and 8 ‰ salinity resulted in higher lysine requirements due to changes in the related nutrient metabolism, which might provide useful information for designing more effective feed formulations for GIFT cultured in different salinity environment.
这项为期62天的研究旨在评估日粮赖氨酸水平（DLL）和盐度对遗传改良尼罗罗非鱼（GIFT）幼鱼生长性能和营养代谢的影响。采用两因素设计，在不同养殖盐度条件下配制了六种添加赖氨酸的日粮（占干物质的1.34%、1.70%、2.03%、2.41%、2.72%和3.04%）。结果表明，补充赖氨酸提高了特定生长率（SGR）和增重率（WG），降低了饲料转化率（FCR）。同时，在盐度为8‰时，鱼的SGR和WG更高，FCR更低。除水分外，8‰盐度使GIFT鱼的全鱼蛋白质、脂肪和灰分含量增加，表明DLL（1.34%）增加了全鱼脂肪含量，DLL（2.41%）增加了全鱼蛋白质含量。适当的DLL上调了雷帕霉素靶蛋白、4EBP-1和S6激酶1等蛋白质代谢相关基因的mRNA水平。然而，0‰盐度降低了这些蛋白质代谢相关基因的mRNA水平，而适当的DLL可以提高肝脏中糖酵解和糖异生的mRNA水平，但降低脂肪生成相关基因的mRNA水平。0‰盐度提高了GLUT2、葡萄糖激酶和G6磷酸酶的mRNA水平；然而，在8‰盐度下，固醇调节元件结合蛋白1和脂肪酸合酶的mRNA水平更高。此外，8‰盐度还提高了血浆总蛋白和胆固醇水平，降低了葡萄糖水平。这些结果表明，不同盐度下赖氨酸的推荐需求量范围为2.03 - 2.20%（0‰）和2.20 - 2.41%（8‰），8‰盐度由于相关营养代谢的变化导致赖氨酸需求量更高，这可能为设计更有效的不同盐度环境下养殖GIFT的饲料配方提供有用信息。
