The present study investigates the effect of different dietary protein levels suboptimum level (25%) and optimum level (35%), different Zn forms bulk zinc oxide (BZnO) or nanoparticles zinc oxide (NZnO), and their interaction on performance, intestinal topography, hematology, serum biochemical, antioxidant-immune responses, and related gene expression of Nile tilapia. Six experimental diets were formulated to contain approximately 25% and 35% crude protein and supplemented with Zn forms with 0 (normal level in ingredients), 60 mg kg-1 BZnO and 60 mg kg-1 nanoparticles of NZnO. Nile tilapia, Oreochromis niloticus, fingerlings (7.53 ± 0. 06 g) were fed on one of tested diets in triplicates with 5% of total biomass three times a day for 84 days. Results showed that, fish fed diet containing 35% crude protein and supplemented with NZnO form recorded the highest final body weight (FBW), weight gain (WG), and specific growth rate (SGR). However, no significant (P > 0.05) differences were recorded in FBW, WG, SGR, feed conversion ratio (FCR), and protein efficiency ratio (PER) between fish fed diet containing 35% crude protein without Zn supplementation and fish fed diet containing 25% crude protein supplemented with NZnO form. Either fish fed diet containing 25% or 35% crude protein and supplemented with NZnO exhibited the highest values of villi height/width. The highest absorption surface area (ASA) was obtained in fish fed diet containing 25% or 35% crude protein and supplemented with BZnO. Hemoglobin (Hb), hematocrit (Hct), and red blood cell count (RBCs) highest values were obtained for fish fed diet containing protein level 35% supplemented with NZnO. Fish fed diet containing protein level 35% and supplemented with NZnO had the lowest value of alanine amino transferase (ALT) and aspartate amino transferase (AST). The highest globulin value was recorded for fish provided with diet containing 35% crude protein and supplemented with BZnO followed by those fed diet containing 35% crude protein and supplemented with NZnO. Fish fed diet containing protein level 25% with NZnO supplementation recorded the highest super oxide dismutase (SOD), catalase (CAT), glutathione reductase (GSH), and glutathione peroxidase (GPX), with decreasing malondialdehyde (MAD) values. The highest values of immunoglobulin g (IgG), immunoglobulin M (IgM), complement 4 (C4), and complement 3 (C3) were obtained for diet containing 35% crude protein and supplemented with NZnO form. Growth hormone gene (GH) was upregulated in fish fed 25% dietary protein without Zn supplementation, while it was downregulated in fish fed 25% dietary protein and supplemented with NZnO. Transcription of insulin-like growth factor-1 (IGF-I) gene recorded the highest value for fish fed 35% crude protein and supplemented with BZnO. This is although the diet of 35% crude protein + NZnO induced significant (IGF-I) gene expression compared with 25% crude protein with or without BZnO. Therefore, nano zinc is useful as a feed supplement for Nile tilapia (Oreochromis niloticus).

中文翻译：

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膳食锌形式补充剂和膳食蛋白质水平对尼罗罗非鱼的性能、肠道功能地形、血液生化指标、免疫、氧化反应和相关基因表达的协同作用。

本研究调查了不同日粮蛋白质水平次优水平 (25%) 和最佳水平 (35%)、不同 Zn 形式的散装氧化锌 (BZnO) 或纳米氧化锌 (NZnO) 的影响，以及它们对性能、肠道形态的相互作用、血液学、血清生化、抗氧化-免疫反应和尼罗罗非鱼的相关基因表达。六种实验日粮的配方分别含有大约 25% 和 35% 的粗蛋白，并添加了 0（成分中的正常水平）、60 mg kg-1 BZnO 和 60 mg kg-1 NZnO 纳米颗粒的 Zn 形式。尼罗罗非鱼、Oreochromis niloticus、鱼种 (7.53 ± 0. 06 g) 一式三份以总生物量的 5% 的试验日粮之一饲喂，每天 3 次，共 84 天。结果表明，喂食含有 35% 粗蛋白并补充 NZnO 形式的鱼饲料记录了最高的最终体重 (FBW)、体重增加 (WG) 和比生长率 (SGR)。然而，在不含锌补充剂的含 35% 粗蛋白的鱼饲料和含锌饲料的鱼饲料之间的 FBW、WG、SGR、饲料转化率 (FCR) 和蛋白质效率比 (PER) 没有显着差异 (P > 0.05) 25% 粗蛋白，辅以 NZnO 形式。喂食含有 25% 或 35% 粗蛋白并补充 NZnO 的鱼的绒毛高度/宽度值最高。在含有 25% 或 35% 粗蛋白并补充 BZnO 的鱼饲料中获得了最高的吸收表面积 (ASA)。血红蛋白 (Hb)、红细胞比容 (Hct)、蛋白质含量为 35% 并添加 NZnO 的鱼饲料获得了最高值和红细胞计数 (RBC)。喂食蛋白质水平为 35% 并补充 NZnO 的鱼的丙氨酸氨基转移酶 (ALT) 和天冬氨酸氨基转移酶 (AST) 的值最低。饲喂含 35% 粗蛋白并添加 BZnO 日粮的鱼的球蛋白值最高，其次是饲喂含 35% 粗蛋白并添加 NZnO 日粮的鱼。喂食蛋白质水平为 25% 并添加 NZnO 的鱼饲料记录了最高的超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、谷胱甘肽还原酶 (GSH) 和谷胱甘肽过氧化物酶 (GPX)，丙二醛 (MAD) 值降低。免疫球蛋白g（IgG）、免疫球蛋白M（IgM）、补体4（C4）的最高值，对于含有 35% 粗蛋白和补充 NZnO 形式的日粮，获得了补体 3 (C3)。生长激素基因 (GH) 在饲喂 25% 日粮蛋白质且未添加锌的鱼中上调，而在饲喂 25% 日粮蛋白质并添加 NZnO 的鱼中下调。在饲喂 35% 粗蛋白并补充 BZnO 的鱼中，胰岛素样生长因子-1 (IGF-I) 基因的转录值最高。这是尽管与含有或不含 BZnO 的 25% 粗蛋白相比，35% 粗蛋白 + NZnO 的饮食诱导了显着的 (IGF-I) 基因表达。因此，纳米锌可用作尼罗罗非鱼（Oreochromis niloticus）的饲料补充剂。生长激素基因 (GH) 在饲喂 25% 日粮蛋白质且未添加锌的鱼中上调，而在饲喂 25% 日粮蛋白质并添加 NZnO 的鱼中下调。在饲喂 35% 粗蛋白并补充 BZnO 的鱼中，胰岛素样生长因子-1 (IGF-I) 基因的转录值最高。这是尽管与含有或不含 BZnO 的 25% 粗蛋白相比，35% 粗蛋白 + NZnO 的饮食诱导了显着的 (IGF-I) 基因表达。因此，纳米锌可用作尼罗罗非鱼（Oreochromis niloticus）的饲料补充剂。生长激素基因 (GH) 在饲喂 25% 日粮蛋白质且未添加锌的鱼中上调，而在饲喂 25% 日粮蛋白质并添加 NZnO 的鱼中下调。在饲喂 35% 粗蛋白并补充 BZnO 的鱼中，胰岛素样生长因子-1 (IGF-I) 基因的转录值最高。这是尽管与含有或不含 BZnO 的 25% 粗蛋白相比，35% 粗蛋白 + NZnO 的饮食诱导了显着的 (IGF-I) 基因表达。因此，纳米锌可用作尼罗罗非鱼（Oreochromis niloticus）的饲料补充剂。这是尽管与含有或不含 BZnO 的 25% 粗蛋白相比，35% 粗蛋白 + NZnO 的饮食诱导了显着的 (IGF-I) 基因表达。因此，纳米锌可用作尼罗罗非鱼（Oreochromis niloticus）的饲料补充剂。这是尽管与含有或不含 BZnO 的 25% 粗蛋白相比，35% 粗蛋白 + NZnO 的饮食诱导了显着的 (IGF-I) 基因表达。因此，纳米锌可用作尼罗罗非鱼（Oreochromis niloticus）的饲料补充剂。