This study investigated the effects of glutamate (Glu) in low‐phosphorus diets on growth performance, haematological indices, antioxidant enzyme activity, immune‐related gene expression and resistance to Aeromonas hydrophila in juvenile mirror carp (Cyprinus carpio) (5.07 ± 0.02 g). Fish were fed either graded levels of Glu (0 g/kg, 5 g/kg, 10 g/kg and 20 g/kg, named G0, G0.5, G1 and G2, respectively) in a low‐phosphorus diet (15 g/kg NaH₂PO_4, 0.49), or a normal phosphorus diet ( 20 g/kg NaH₂PO_4, 0.61) without added Glu (C), for 8 weeks. At the end of the feeding trial, the fish were challenged with A. hydrophila. Compared with G0 group, 10 g/kg and 20 g/kg Glu supplementation of the low‐phosphorus diet significantly improved the final weight, WGR, SGR and PER, and decreased FCR (p < .05). Glu supplementation of the low‐phosphorus diet significantly enhanced the T‐AOC, SOD activity and GSH content in intestine (p < .05). Glu supplementation significantly reduced MDA content in foregut and midgut and increased CAT activity in midgut and hindgut (p < .05). Regarding immune‐related gene expression, Glu supplementation significantly diminished the up‐regulation of intestinal TNF‐α, IL‐1β and IL‐8 mRNA levels induced by phosphorus deficiency (p < .05). The survival rate of the G1 group was significantly higher than that of the G0 group (p < .05). In conclusion, 10 g/kg Glu supplementation in low‐phosphorus diets can improve the growth performance, enhance the activity of intestinal antioxidant enzymes and strengthen the immune function of juvenile mirror carp.

中文翻译：

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低磷日粮中谷氨酸对幼年鲤的生长性能，抗氧化酶活性，免疫相关基因表达和对嗜水气单胞菌抗性的影响

这项研究调查了低磷饮食中的谷氨酸（Glu）对幼年镜鲤（Cyprinus carpio）（5.07±0.02 g）的生长性能，血液学指标，抗氧化酶活性，免疫相关基因表达和对嗜水气单胞菌抗性的影响。。在低磷饮食中给鱼类饲喂两种等级的Glu（0 g / kg，5 g / kg，10 g / kg和20 g / kg，分别命名为G0，G0.5，G1和G2）。克/公斤的NaH ₂ PO _4， 0.49），或正常饮食磷（20克/千克的NaH ₂ PO _4， 0.61）没有添加谷氨酸（C），8周。在饲养试验结束时，将鱼用嗜水链球菌攻击。与G0组相比，低磷饮食补充10 g / kg和20 g / kg Glu可以显着改善最终体重，WGR，SGR和PER，并降低FCR（p  <.05）。低磷饮食的谷氨酸补充显着提高了肠道中的T-AOC，SOD活性和GSH含量（p  <.05）。补充谷氨酸显着降低了前肠和中肠的MDA含量，并增加了中肠和后肠的CAT活性（p  <.05）。关于免疫相关基因的表达，Glu的添加显着减少了磷缺乏引起的肠道TNF-α，IL-1β和IL-8 mRNA的上调（p  <.05）。G1组的生存率明显高于G0组（p  <.05）。总之，在低磷日粮中添加10 g / kg Glu可以改善生长性能，增强肠道抗氧化酶的活性，并增强幼体鲤鱼的免疫功能。