Effects of dietary lysine levels on growth performance, whole body composition and gene expression related to glycometabolism and lipid metabolism in grass carp, Ctenopharyngodon idellus fry
Effects of dietary lysine levels on growth performance, whole body composition and gene expression related to glycometabolism and lipid metabolism in grass carp, Ctenopharyngodon idellus fry
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DOI：
10.1016/j.aquaculture.2020.735806
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发表时间：
2021-01-15
期刊：
影响因子：
4.5
通讯作者：
Maulu, Sahya
中科院分区：
文献类型：
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作者：
Huang, Dongyu;Liang, Hualiang;Maulu, Sahya
本试验旨在评估草鱼对饲料赖氨酸的需用量，并评价饲料赖氨酸对草鱼鱼苗糖代谢和脂代谢的影响。配制6种实用饲料，分别饲喂720尾初重0.36 +/- 0.00 g、赖氨酸水平分别为1.44%、1.79%、1.97%、2.44%、2.56%和2.87%的干饲料。结果表明：与对照组（赖氨酸水平为1.44%）相比，饲粮中添加2.44%赖氨酸可显著提高末重（FBW）、增重率（WGR）和特定生长率（SGR），且与采食量（FI）和饲料系数（FCR）相当。随着饲料赖氨酸水平的升高，全鱼脂质含量由1.44%降至2.44%，随后升高。糖代谢方面，与对照组相比，2.44%赖氨酸水平通过提高葡萄糖激酶（GK）和丙酮酸激酶（PK） mRNA水平显著改善糖酵解，2.87%赖氨酸水平通过提高磷酸烯醇丙酮酸羧激酶（PEPCK）和葡萄糖-6-磷酸酶（G6Pase） mRNA水平显著促进糖异生。糖原合成酶（GS） mRNA水平与饲料处理无关。在脂肪分解途径中，饲粮赖氨酸水平为2.44%导致PPAR信号通路中激素敏感脂肪酶（HSL）、脂肪甘油三酯脂肪酶（ATGL）和肉毒碱棕榈酰转移酶-1 (CPT1) mRNA水平上调。与脂肪酸合成酶（FAS）、乙酰辅酶a羧化酶-1 （ACC1）和硬脂酰辅酶a去饱和酶（SCD）一样，PPAR信号通路中与脂质合成相关的过氧化物酶体增殖物活化受体γ (PPAR- γ) mRNA的相对表达量不受饲料赖氨酸水平的显著影响。此外，所有处理均未明显影响肠道中甾醇调节元件结合蛋白1 (SREBP1) mRNA水平。折线回归分析表明，以SGR和FCR为指标，草鱼鱼苗对饲料赖氨酸的适宜需用量分别为饲料赖氨酸的2.39%和2.13%（占饲料蛋白质的6.34%和5.65%）。综上所述，饲粮赖氨酸水平适宜（2.44%）可提高生长性能，降低全身脂质，促进糖酵解和脂肪分解。
8 weeks rearing trial was designed to estimate the dietary lysine requirement, and evaluate the effects of dietary lysine on glycometabolism and lipid metabolism of grass carp fry. Six practical diets were prepared to feed 720 fish (initial weight 0.36 +/- 0.00 g) with graded lysine levels (1.44%, 1.79%, 1.97%, 2.44%, 2.56% and 2.87%, dry diet). The results displayed that the final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) were significantly improved by 2.44% dietary lysine, the same as feed intake (FI) and feed conversion ratio (FCR), compared with those of the control group (1.44% dietary lysine). Whole-body lipid contents diminished with raising dietary lysine levels from 1.44% to 2.44% and thereafter the content increased. Regarding glycometabolism, compared to the control diet, the 2.44% dietary lysine level significantly improved glycolysis by increasing glucokinase (GK) and pyruvate kinase (PK) mRNA levels, meanwhile the 2.87% dietary lysine level promoted gluconeogenesis by significantly increasing phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) mRNA levels. Glycogen synthase (GS) mRNA levels were independent of dietary treatment. For the lipolysis pathway, the 2.44% dietary lysine level caused the upregulation of hormone sensitive lipase (HSL), adipose triglyceride lipase (ATGL) and carnitine palmitoyl transferase-1 (CPT1) mRNA levels in the PPAR signaling pathway. Like the fatty acid synthase (FAS), acetyl-CoA carboxylase-1 (ACC1) and stearyl-CoA desaturase (SCD), the relative mRNA expression of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) related to lipid synthesis in the PPAR signaling pathway, was not remarkably influenced by dietary lysine levels. Furthermore, sterol-regulatory element binding protein-1 (SREBP1) mRNA levels in the intestine were not clearly affected among all the treatments. According to the broken-line regression analysis, based on the SGR and FCR, the optimum requirements of grass carp fry for dietary lysine were 2.39% and 2.13% of diet (6.34% and 5.65% of dietary protein), respectively. Overall, appropriate dietary lysine levels (2.44%) could improve the growth performance, reduce the whole-body lipid, promote glycolysis and lipolysis.