Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana 61801, USA.
Poult Sci. 2013 Jan;92(1):171-7. doi: 10.3382/ps.2012-02425.
Guanidino acetic acid (GAA) is synthesized in the liver and kidney from Arg and Gly and subsequently methylated by S-adenosylmethionine to form creatine. Four bioassays were carried out to determine the capacity of GAA to serve as a dietary replacement for Arg for growing chicks. Broiler chicks were fed Arg-deficient dextrose-casein (0.88% Arg) or corn-corn coproduct-soybean meal (1.0% Arg) basal diets during 9-d battery feeding trials involving 5 pens of 4 chicks per treatment. The dextrose-casein diet was shown to be markedly deficient in Arg as both weight gain and G:F increased (P < 0.01) due to addition of Arg, GAA, or creatine. The optimal level of added GAA was 0.12% of the diet, but this level of GAA or 1.0% creatine-H(2)O did not improve growth performance when added to an Arg-adequate diet. A second assay confirmed this level of optimal Arg in a 2 × 2 factorial arrangement of l-Arg and GAA supplementation. Using a practical-type diet based on corn, corn gluten meal, distillers dried grains with solubles, and soybean meal, similar improvements (P < 0.05) in G:F resulted from addition of 0.25% Arg, 0.12% GAA, or 0.15% creatine·H(2)O. These results demonstrate that 0.12% supplemental GAA, like creatine, produces consistent growth responses in young chicks fed Arg-deficient diets. To provide further evidence of the capacity for GAA to serve as a dietary Arg replacement, the dextrose-casein diet was supplemented with 7 graded doses of Arg in the absence or presence of 0.12% GAA (14 total diets). Quadratic (P < 0.01) responses in weight gain and G:F responses to supplemental Arg were observed. Similar supplemental Arg requirements were estimated in the absence and presence of 0.12% GAA, but GAA elicited a greater improvement (P < 0.05) in G:F when added to Arg-deficient, compared with Arg-adequate, diets. Collectively, these data indicate that GAA can be used as an efficacious replacement for dietary Arg for young chicks.
胍基乙酸（GAA）在肝脏和肾脏中由精氨酸（Arg）和甘氨酸（Gly）合成，并随后由 S-腺苷甲硫氨酸（SAM）甲基化为肌酸。进行了四项生物测定，以确定 GAA 作为生长小鸡的 Arg 替代物的能力。肉鸡雏鸡在 9 天的电池喂养试验中分别用缺乏精氨酸的葡萄糖-酪蛋白（0.88%Arg）或玉米-玉米副产物-豆粕（1.0%Arg）基础日粮进行喂养，涉及 5 个处理的 4 个鸡笼。由于添加了 Arg、GAA 或肌酸，葡萄糖-酪蛋白日粮明显缺乏 Arg，导致体重增加和饲料转化率（G:F）增加（P<0.01）。添加 GAA 的最佳水平为日粮的 0.12%，但当添加到 Arg 充足的日粮中时，该水平的 GAA 或 1.0%肌酸-H（2）O 并不能改善生长性能。第二项测定在 l-Arg 和 GAA 补充的 2×2 析因安排中证实了这种最佳 Arg 水平。使用基于玉米、玉米蛋白粉、酒糟干物质和豆粕的实用型日粮，添加 0.25%Arg、0.12%GAA 或 0.15%肌酸·H（2）O 可使 G:F 得到类似的改善（P<0.05）。这些结果表明，0.12%的补充 GAA 与肌酸一样，可使饲喂 Arg 缺乏日粮的小鸡产生一致的生长反应。为了提供 GAA 作为膳食 Arg 替代物的能力的进一步证据，在缺乏或存在 0.12%GAA 的情况下，用葡萄糖-酪蛋白日粮补充 7 个梯度剂量的 Arg（共 14 个日粮）。在补充 Arg 时，观察到体重增加和 G:F 反应的二次（P<0.01）反应。在缺乏和存在 0.12%GAA 的情况下，估计了类似的补充 Arg 需求，但与 Arg 充足的日粮相比，添加 GAA 可使 G:F 得到更大的改善（P<0.05）。综上所述，这些数据表明 GAA 可以用作幼鸡有效的日粮 Arg 替代物。
