Two separate comparative feeding trials were conducted to evaluate if supplemental dietary guanidinoacetic acid (GDA), either singly or in combination with creatine, could enhance growth performance of red drum. The basal diet for both trials was formulated with practical ingredients but was not supplemented with creatine or GDA. For the experimental diets, creatine (0 or 20 g/kg) and GDA (0, 5 or 10 g/kg) were added to the basal diet in a 2 × 3 factorial arrangement for trial 1. Another 2 × 3 experimental design was adopted in trial 2 to further evaluate creatine (0 or 20 g/kg) and GDA (0, 10 or 20 g/kg) supplementation. Each diet was fed to juvenile red drum in either quadruplicate (trial 1) or triplicate (trial 2) aquaria twice daily for a total of 8 weeks. After each feeding trial, fish were sampled for body condition indices and whole‐body composition analysis, as well as determination of plasma, liver and muscle creatine concentrations. In trial 1, dietary creatine supplementation alone significantly (p < .05) improved weight gain and feed efficiency of red drum. An interaction between creatine and GDA was seen in whole‐body protein and lipid in the two trials. In trial 1, the highest levels of whole‐body protein and lipid were observed in fish fed 10 g GDA/kg, and in trial 2, supplementation of the diet with 10 g GDA/kg increased muscle protein and muscle lipid although there was a trending decline in fish fed the 20 g/kg GDA‐supplemented diet. In both trials of the present study, dietary GDA significantly (p < .05) enhanced liver creatine content. Dietary creatine also significantly (p < .05) enhanced plasma and muscle creatine content of red drum. Based on the results of this study, creatine was effective in enhancing weight gain and feed efficiency of red drum as seen in previous studies; however, GDA was not effective in influencing growth performance but limited synthesis of creatine from dietary GDA was apparent.

中文翻译：

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日粮中添加肌酸和胍基乙酸对红鼓鱼幼鱼的评价

进行了两项独立的比较喂养试验，以评估补充膳食胍基乙酸 (GDA) 是否可以单独或与肌酸组合提高红鼓的生长性能。两项试验的基础饮食均采用实用成分配制，但未添加肌酸或 GDA。对于实验日粮，肌酸（0 或 20 克/公斤）和 GDA（0、5 或 10 克/公斤）以 2 × 3 因子排列添加到基础日粮中，用于试验 1。另一个 2 × 3 实验设计是在试验 2 中采用以进一步评估肌酸（0 或 20 g/kg）和 GDA（0、10 或 20 g/kg）补充剂。将每种饮食以一式四份（试验 1）或一式三份（试验 2）水族箱饲喂幼鱼，每天两次，共 8 周。每次喂食试验后，对鱼进行取样以进行身体状况指数和全身成分分析，以及血浆、肝脏和肌肉肌酸浓度的测定。在试验 1 中，单独添加日粮肌酸显着 (p < .05) 提高了红鼓的增重和饲料效率。在两项试验中，在全身蛋白质和脂质中观察到肌酸和 GDA 之间的相互作用。在试验 1 中，在饲喂 10 g GDA/kg 的鱼中观察到最高水平的全身蛋白质和脂质，在试验 2 中，在饮食中补充 10 g GDA/kg 增加了肌肉蛋白质和肌肉脂质，尽管有喂食 20 g/kg GDA 补充饮食的鱼的趋势下降。在本研究的两项试验中，膳食 GDA 显着 (p < .05) 提高了肝肌酸含量。膳食肌酸也显着（p < . 05) 提高红鼓的血浆和肌肉肌酸含量。根据这项研究的结果，肌酸可有效提高红鼓的增重和饲料效率，正如之前的研究所见；然而，GDA 不能有效影响生长性能，但饮食 GDA 中肌酸的合成有限。