Torreele E, van der Sluiszen A, Verreth J
Department of Fish Culture and Fisheries, Wageningen Agricultural University, The Netherlands.
Br J Nutr. 1993 Jan;69(1):289-99. doi: 10.1079/bjn19930030.
The effect of dietary L-carnitine on the growth and growth efficiency of African catfish (Clarias gariepinus, Burchell 1822) fingerlings was investigated. Six dietary levels of L-carnitine, varying from the control level (about 125 mg/kg) to 3920 mg/kg, were each tested at two dietary lipid levels (96 and 155 g/kg). The diets were isonitrogenous and were fed to thirty-six experimental groups of 100 fish weighing 5 g at a feeding level of 25.2 g/kg live weight (w)0.8 per d, during 18 d. The average final weight varied from 19.1 to 28.0 g. At a dietary lipid level of 96 g/kg the metabolic growth increased from 30.8 to 36.5 g/kg w0.8 per d. At the higher dietary lipid level the metabolic growth increased from 30.9 to 35.4 g/kg w0.8 per d. To assess the dose-response relationship between dietary L-carnitine and growth performance in the African catfish a linear-plateau model was fitted to the experimental data. According to this model, metabolic growth was at a maximum at L-carnitine levels of 500 mg/kg and above at a lipid level of 96 g/kg and at L-carnitine levels of 684 mg/kg and above at a lipid level of 155 g/kg. The fitted maximum metabolic growth was higher at a dietary lipid level of 96 g/kg (35.9 g/kg w0.8 per d) than at 155 g/kg (34.7 g/kg w0.8 per d). Feed conversion improved significantly with increasing dietary levels of L-carnitine, reaching a fitted plateau at L-carnitine levels of 448.8 and 236.7 mg/kg respectively for the high and low dietary fat levels. Other growth efficiency variables, e.g. protein efficiency ratio, protein retention and energy retention improved accordingly. Taking into consideration that all fish received the same amount of feed, the results of the present study demonstrate that the positive effect of increased levels of dietary L-carnitine is the result of an improved feed utilization, probably because of a stimulated protein-sparing action.
研究了日粮中L-肉碱对非洲鲶鱼（Clarias gariepinus，Burchell 1822）幼鱼生长及生长效率的影响。设置了六个L-肉碱日粮水平，从对照水平（约125毫克/千克）到3920毫克/千克，每个水平在两种日粮脂肪水平（96克/千克和155克/千克）下进行测试。日粮等氮，以25.2克/千克活体重（w）0.8的投喂水平，每日投喂给36个实验组，每组100尾体重5克的鱼，持续18天。平均终末体重在19.1至28.0克之间。在日粮脂肪水平为96克/千克时，代谢生长从30.8克/千克w0.8/天增加到36.5克/千克w0.8/天。在较高的日粮脂肪水平下，代谢生长从30.9克/千克w0.8/天增加到35.4克/千克w0.8/天。为评估日粮L-肉碱与非洲鲶鱼生长性能之间的剂量反应关系，对实验数据拟合了线性-平台模型。根据该模型，在脂肪水平为96克/千克时，L-肉碱水平达到500毫克/千克及以上时代谢生长达到最大值；在脂肪水平为155克/千克时，L-肉碱水平达到684毫克/千克及以上时代谢生长达到最大值。日粮脂肪水平为96克/千克时拟合的最大代谢生长（35.9克/千克w0.8/天）高于155克/千克时（34.7克/千克w0.8/天）。随着日粮L-肉碱水平的增加，饲料转化率显著提高，在高、低日粮脂肪水平下，L-肉碱水平分别达到448.8毫克/千克和236.7毫克/千克时达到拟合平台。其他生长效率变量，如蛋白质效率比、蛋白质保留率和能量保留率也相应提高。考虑到所有鱼摄入的饲料量相同，本研究结果表明，日粮中L-肉碱水平增加的积极作用是饲料利用率提高的结果，可能是由于蛋白质节省作用受到刺激。
