Fracalossi D M, Allen M E, Nichols D K, Oftedal O T
Department of Zoological Research, National Zoological Park, Smithsonian Institution, Washington, DC 20008, USA.
J Nutr. 1998 Oct;128(10):1745-51. doi: 10.1093/jn/128.10.1745.
We found that vitamin C is an essential nutrient for an Amazonian ornamental fish, the oscar (Astronotus ocellatus). This was demonstrated by the absence of L-gulonolactone oxidase activity, the enzyme responsible for the biosynthesis of vitamin C, in liver or kidney of oscars and by a feeding trial in which oscars without vitamin C dietary supplementation developed clinical deficiency signs. Fish weighing 29.2 +/- 1.9 g were divided into four groups, and each group was fed a casein-based semipurified diet containing 0, 25, 75 or 200 mg ascorbic acid equivalent (AA)/kg diet for 26 wk. Vitamin C was supplemented in the diets as L-ascorbyl-2-polyphosphate, a mixture of phosphate esters of ascorbate, which is more stable to oxidation than AA. At the end of 26 wk, fish fed no AA had significantly lower weight gain than fish fed the AA-supplemented diets (P < 0.05). Oscars without dietary AA supplementation gained only 37% of their initial weight, compared with 112, 102 and 91% gained by fish fed 25, 75 and 200 mg AA/kg diet, respectively. After 25 wk without dietary supplementation of AA, fish began to develop clinical deficiency signs, including deformed opercula and jaws, hemorrhage in the eyes and fins, and lordosis. Histology indicated that fish without AA supplementation had deformed gill filament support cartilage and atrophied muscle fibers. Collagen content of the vertebral column was significantly lower in fish devoid of dietary AA (P < 0.05). Liver AA concentration varied in proportion to dietary concentration of AA. The minimum dietary AA concentration tested in this study, 25 mg AA/kg diet, was sufficient to prevent growth reduction and AA deficiency signs in oscars.
我们发现维生素C是一种亚马逊观赏鱼——奥斯卡鱼（眼斑丽鱼）必需的营养素。奥斯卡鱼的肝脏或肾脏中缺乏L-古洛糖酸内酯氧化酶活性（该酶负责维生素C的生物合成），以及一项喂养试验证明了这一点。在该喂养试验中，未补充维生素C饮食的奥斯卡鱼出现了临床缺乏症状。将体重为29.2±1.9克的鱼分为四组，每组喂食以酪蛋白为基础的半纯化日粮，日粮中含有0、25、75或200毫克抗坏血酸当量（AA）/千克日粮，持续26周。日粮中添加的维生素C为L-抗坏血酸-2-多聚磷酸酯，这是一种抗坏血酸的磷酸酯混合物，其抗氧化稳定性高于AA。在26周结束时，未喂食AA的鱼的体重增加显著低于喂食补充了AA日粮的鱼（P<0.05）。未补充日粮AA的奥斯卡鱼体重仅增加了其初始体重的37%，而喂食25、75和200毫克AA/千克日粮的鱼体重分别增加了112%、102%和91%。在25周未补充日粮AA后，鱼开始出现临床缺乏症状，包括鳃盖和颌骨变形、眼睛和鳍出血以及脊柱前凸。组织学检查表明，未补充AA的鱼鳃丝支撑软骨变形，肌肉纤维萎缩。缺乏日粮AA的鱼脊柱胶原含量显著降低（P<0.05）。肝脏AA浓度与日粮中AA浓度成比例变化。本研究中测试的最低日粮AA浓度，即25毫克AA/千克日粮，足以防止奥斯卡鱼生长减缓及出现AA缺乏症状。
