The objective was to elucidate the effects of dietary supplementation with guanidinoacetic acid (GAA) on performance, egg quality and the liver antioxidant activity of laying hens. A total of 128, 72-week-old ISA Brown laying hens were randomly divided into four equal groups (32 birds), and each subgroup had eight replicates (four birds/cage). The control group (GAA0) fed the basal diet with no supplements, while the other experimental groups fed the basal diets supplemented with 0.5 (GAA1), 1.0 (GAA2) and 1.5 (GAA3) g of GAA/kg diet. The experiment lasted for 6 weeks. The addition of GAA at a rate of 1.5 g kg−1 significantly increased the hen-day egg production and egg mass as compared to the control group (P = 0.016 and 0.003, respectively). Although the egg weight was not affected (P = 0.521) by the dietary supplements, the shell ratio, shell thickness, yolk index and Haugh units increased linearly with the increase in the dietary supplements of the GAA (P = 0.036, 0.001, 0.012 and 0.004, respectively). The liver MDA levels decreased linearly with the increment in the dietary levels of the GAA (P = 0.012). Birds in the GAA2 and GAA3 showed a significantly higher liver nitric oxide level (52.50 and 54.21 mg/g, respectively) when compared with GAA0 and GAA1 groups (P = 0.029). Compared to the GAA0 group, all GAA-supplemented groups showed significantly higher liver ATP levels (P = 0.047). In conclusion, the dietary GA supplements at doses of 1.0 or 1.5 g kg−1 may improve the laying performance, antioxidant activity and the status of cellular energy metabolism in laying hens.

中文翻译：

---

添加胍基乙酸对产蛋鸡后期产蛋性能、蛋品质、肝脏一氧化氮及能量代谢的影响

目的是阐明日粮中添加胍基乙酸 (GAA) 对蛋鸡生产性能、蛋品质和肝脏抗氧化活性的影响。总共 128 只 72 周龄的 ISA Brown 蛋鸡被随机分成 4 个相等的组（32 只鸡），每个亚组有 8 个重复（4 只鸡/笼）。对照组（GAA0) 饲喂基础日粮，不添加任何补充剂，而其他实验组饲喂添加 0.5 (GAA) 的基础日粮1), 1.0 (GAA2) 和 1.5 (GAA3) g GAA/kg 饮食。实验持续了 6 周。以 1.5 g kg 的速率添加 GAA-1与对照组相比，母鸡日产蛋量和蛋重显着增加（磷= 0.016 和 0.003，分别）。虽然蛋重不受影响（磷= 0.521) 由膳食补充剂组成，壳比、壳厚度、蛋黄指数和 Haugh 单位随着 GAA 膳食补充剂的增加呈线性增加 (磷= 0.036、0.001、0.012 和 0.004）。肝脏 MDA 水平随着 GAA 膳食水平的增加呈线性下降（磷= 0.012)。GAA 中的鸟类2和GAA3与 GAA 相比，肝脏一氧化氮水平显着升高（分别为 52.50 和 54.21 mg/g）0和GAA1组（磷= 0.029)。与 GAA 相比0组中，所有补充 GAA 的组均显示出显着更高的肝脏 ATP 水平（磷= 0.047)。总之，膳食 GA 补充剂的剂量为 1.0 或 1.5 g kg-1可改善蛋鸡的产蛋性能、抗氧化活性和细胞能量代谢状态。