Abstract: This study aimed to determine the effect of dietary tryptophan（Trp）levels on antioxidant ability and Trp requirement for laying duck breeders. A total of 504 Longyan breeding ducks（body weight：1.20 ± 0.02 kg）aged 22 weeks were randomly allocated to 6 treatments，each with 6 replicates of 14 ducks. During the following 16 weeks，birds of differenttreatments were fed the basal diet with total Trp contents of 1.00，2.00，3.00，4.00，5.00 and 6.00 g/kg，respectively. The results showed that the dietary Trp level of 2 g/kg could result in the highest T?SOD activity in plasma（P<0.05），and the plasma serotonin content increased linearly and quadratically with dietary Trp supplemental levels（P<0.05）. The content of T?SOD and T?AOC in liver increased linearly and quadratically，and hepatic MDA content was lowest with dietary Trp level being 2 g/kg（P<0.05）. The gene expression of hepatic GPx1，SOD and Nrf2 increased linearly and quadratically， and the highest values was with Trp level of 4，2 and 1 g/kg，respectively（P<0.05）. The content of T?SOD and T?AOC in jejunum increased linearly and quadratically，and jejunal MDA content was lowest with the dietary Trp level of 3 g/kg（P< 0.05）. The gene expression of jejunal HO?1 and Nrf2 increased linearly and quadratically（P<0.05）. Collectively，dietary Trp level of 2 to 3 g/kg could improve the antioxidant ability in plasma，liver and jejunum in laying breeding ducks.

Key words: Tryptophan, Laying breeding duck, Antioxidant ability

摘要： 该试验旨在通过研究饲粮色氨酸水平对蛋种鸭抗氧化性能的影响，探究蛋鸭饲粮 色氨酸的适宜添加水平。试验选用体重和产蛋性能相近，健康的22周龄福建龙岩山麻蛋鸭 504只，随机分为6个处理，每个处理6个重复，每个重复14只鸭，单笼饲养，试验期为16周。 采用单因子完全随机设计，饲粮中色氨酸的水平分别为：1.0、2.0、3.0、4.0、5.0、6.0 g/kg。结果表 明：1）饲粮色氨酸水平为2 g/kg时，蛋种鸭血浆T?SOD活性最高（P<0.05）；血浆5?羟色胺活性 随饲粮色氨酸水平升高呈线性和二次增加（P<0.05），对褪黑素无显著影响（P>0.05）。 2）蛋种 鸭肝脏T?SOD和T?AOC活性随饲粮色氨酸水平增加呈线性和二次增加，MDA含量在2 g/kg处 最低，对GSH?Px活性无显著影响（P>0.05）；肝脏GPx1、SOD和Nrf2表达量随饲粮色氨酸水平增 加呈线性和二次变化，分别在4 g/kg、2 g/kg、1 g/kg处获得最大值（P<0.05）。3）蛋种鸭空肠T? SOD和T?AOC活性随饲粮色氨酸水平增加呈线性和二次增加，MDA在3 g/kg处含量最低（P< 0.05），对GSH?Px含量无显著影响（P>0.05）；HO?1和Nrf2表达量随饲粮色氨酸水平增加呈线性 和二次变化增加（P<0.05），对SOD表达量无显著影响（P>0.05）。综上所述，饲粮中适宜色氨酸 （2—3 g/kg），可通过增强蛋种鸭血浆、肝脏和空肠抗氧化酶活性，提高机体抗氧化性能。

关键词: 色氨酸, 蛋种鸭, 抗氧化性能