This study was conducted to evaluate the effect of dietary vitamin D (VD) levels on growth, serum biochemical parameters and lipid metabolism in the liver for orange‐spotted grouper (Epinephelus coioides). The fish (initial weight 81.50 ± 0.05 g) were fed diets containing different VD levels (i.e., 0, 500, 1000, 2000, 4000 and 10,000 IU/kg) for 10 weeks. With the increasing level of VD, the weight gain rate (WGR) and the specific growth rate initially increased and then decreased, and the feed conversion ratio significantly decreased in fish supplemented with dietary VD of 1000 IU/kg compared with control group (p < .05). Diet with VD 1000 IU/kg significantly (p < .05) increased the whole‐body crude protein. In the liver, the lipid content decreased while the VD deposition increased significantly (p < .05). VD had significant (p < .05) positive effects on the serum biochemical parameters and lipid metabolism enzyme activities in the liver. Moreover, VD supplementation significantly inhibited the FAS mRNA expression and promoted the HL mRNA expression (p < .05). The broken‐line model of the WGR corresponding to the VD levels indicated that the optimal supplement of dietary VD was 750.19 IU/kg. Diet with VD supplement from 1000 to 2000 IU/kg significantly improved the lipid metabolism in the liver for grouper (p < .05).

中文翻译：

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日粮维生素D水平对生长中期橙斑石斑鱼（Epinephelus coioides）生长，血清生化参数，脂质代谢酶活性，脂肪酸合酶和肝脂肪酶mRNA表达的影响

这项研究旨在评估饮食中维生素D（VD）水平对桔斑石斑鱼（Epinephelus coioides）的生长，血清生化参数和肝脏脂质代谢的影响。给鱼（初始体重81.50±0.05 g）喂食含有不同VD水平（即0、500、1000、2000、4000和10,000 IU / kg）的饲料，持续10周。随着VD水平的升高，增重率（WGR）和比生长率先升高然后降低，并且饲料添加比例为1000 IU / kg的VD的鱼的饲料转化率与对照组相比显着降低（p  < .05）。VD 1000 IU / kg的饮食显着（p <.05）增加了全身粗蛋白。在肝脏中，脂质含量降低，而VD沉积显着增加（p  <.05）。VD 对肝脏中的血清生化参数和脂质代谢酶活性具有显着（p <.05）积极影响。此外，VD补充显着抑制FAS mRNA表达并促进HL mRNA表达（p  <.05）。与VD水平相对应的WGR折线模型表明，膳食VD的最佳补充量为750.19 IU / kg。日粮中添加VD补充剂1000至2000 IU / kg可以明显改善石斑鱼肝脏中的脂质代谢（p  <.05）。