Abstract In this study, the effects of different levels of dietary guanidinoacetic acid (GAA) supplementation (0, 0.6, 1.2 and 1.8 g/kg) in laying quails was evaluated in a completely randomised design comprised of four dietary treatments of six replicates each, from 56 to 154 d of age. The highest laying rate was obtained with 1.8 g/kg of GAA, but the optimum egg weight, egg mass, shell and yolk weight were observed at 1.2 g/kg of GAA. The villus height and villus height: crypt depth ratio of ileum and apparent ileal digestibility of dry matter, crude protein, ether extract and ash were linearly and quadratically affected by GAA supplementation. Maximum glutathione peroxidase and superoxide dismutase enzyme activity and total antioxidant capacity, but minimum malondialdehyde in the serum were observed at 1.2 g/kg of GAA. The highest concentrations of very low-density lipoprotein-cholesterol, total cholesterol and creatine (CRE) were observed at 1.2 g/kg of GAA, whereas the serum low-density lipoprotein-cholesterol (LDL) was at its lowest level. The CRE, nitric oxide and homocysteine concentrations were highest when GAA at 1.8 g/kg was fed, but the highest concentration of total protein and VLDL were observed at 1.2 g/kg of GAA. The betaine content of liver was at its lowest level at 1.8 g/kg GAA supplementation, but the highest levels of total protein and total lipids were observed at 0.6 and 1.8 g/kg of GAA. In conclusion, the results indicate that GAA, especially at 1.2 g/kg, could improve performance, antioxidant status and intestinal performance in laying quails. Highlights Supplementation of GAA up to 1.8 g/kg of the laying quail diet increased egg production rate but liver betaine content decreased by inclusion of more than 1.2 g/kg of GAA. Supplementation of GAA at all studied levels improved nutrient digestibility while the benefits of GAA on intestinal morphology observed at inclusion levels of 0.6 and 1.2 g/kg. The serum and liver antioxidant status of laying quails improved by dietary addition of GAA at 0.6 and 1.2 g/kg levels.

中文翻译：

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日本鹌鹑的性能、抗氧化状态、营养保留和血清特征对增加日粮胍基乙酸添加水平的反应

摘要 在本研究中，在完全随机设计中评估了不同水平的日粮胍基乙酸 (GAA) 补充剂（0、0.6、1.2 和 1.8 g/kg）对蛋鹌鹑的影响，该设计由四个日粮处理组成，每个处理六个重复，从 56 到 154 日龄。1.8 g/kg GAA 的产蛋率最高，但观察到最佳蛋重、蛋重、蛋壳和蛋黄重量为 1.2 g/kg GAA。绒毛高度和绒毛高度：回肠的隐窝深度比和干物质、粗蛋白、醚提取物和灰分的表观回肠消化率受 GAA 补充的线性和二次影响。谷胱甘肽过氧化物酶和超氧化物歧化酶活性和总抗氧化能力最大，但血清中丙二醛在 1.2 g/kg GAA 时观察到最小。在 1.2 g/kg GAA 时观察到极低密度脂蛋白胆固醇、总胆固醇和肌酸 (CRE) 的最高浓度，而血清低密度脂蛋白胆固醇 (LDL) 处于最低水平。当饲喂 1.8 g/kg GAA 时，CRE、一氧化氮和同型半胱氨酸浓度最高，但在 1.2 g/kg GAA 时观察到最高浓度的总蛋白和 VLDL。肝脏中甜菜碱含量在添加 1.8 g/kg GAA 时处于最低水平，但在 0.6 和 1.8 g/kg GAA 时观察到最高水平的总蛋白和总脂质。总之，结果表明 GAA，尤其是 1.2 g/kg，可以提高产蛋鹌鹑的性能、抗氧化状态和肠道性能。突出显示 GAA 的补充高达 1。8 g/kg 的产蛋鹌鹑日粮提高了产蛋率，但肝脏甜菜碱含量因包含超过 1.2 g/kg 的 GAA 而降低。在所有研究水平下补充 GAA 都提高了营养物质的消化率，而在 0.6 和 1.2 g/kg 的加入水平下观察到 GAA 对肠道形态的益处。通过在日粮中添加 0.6 和 1.2 g/kg 的 GAA，蛋鹌鹑的血清和肝脏抗氧化状态得到改善。