The present study was aimed to compare and evaluate the impacts of supplemented diets with different yeast hydrolysate (YH) levels on growth performance, body composition, hematological characteristics, antioxidant enzyme activities, and non-specific immunity (intestinal cytokines) of juvenile Nile tilapia (Oreochromis niloticus). Three isonitrogenous (protein, 33%) and isolipidic (lipid, 6%) experimental diets supplemented graded levels of YH (0% for control; 1% and 3% as tested diets) were fed to juvenile Nile tilapia. A total of 240 fish with initial body weight averaging 3.5 ± 0.02 g were randomly divided into three groups with four replicates per group and 20 fish for each replicate. For apparent satiation, the fish were fed twice daily during eight weeks. The results showed no significant difference in survival among all treatments. The fish fed the diet containing 1% yeast hydrolysate had significantly elevated weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) compared to the control group and lower feed conversion ratio (FCR). The fish fed 1% and 3% YH showed higher glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) activity and a significantly lower malondialdehyde (MDA) level in the liver than the control group, indicating enhancement of the anti-oxidant status. Serum lysozyme activity was significantly increased in the diet having 1% and 3% yeast hydrolysate supplementation groups, suggesting an improvement influence on the non-specific immune response. The expression of IL-1β, IL-10, TNF-α, TGF-β2, ALP and TLR2 was significantly elevated in fish fed the diet containing 1% YH. In conclusion, dietary supplementation with 1% yeast hydrolysate improves growth performance, and feed utilization enhances the antioxidant status and exerts an adequate stimulus on the non-specific immunity (intestinal cytokines) of Nile tilapia.

中文翻译：

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日粮酵母水解物对幼年尼罗罗非鱼，尼罗罗非鱼的生长，血液学，抗氧化酶活性和非特异性免疫的影响。

本研究旨在比较和评估不同酵母水解物（YH）水平的补充饮食对尼罗罗非鱼幼鱼生长性能，身体成分，血液学特征，抗氧化酶活性和非特异性免疫力（肠道细胞因子）的影响。尼罗罗非鱼（Oreochromis niloticus）。将三种补充了YH分级水平的等氮（蛋白质，33％）和等脂（脂质，6％）实验饲料（对照组为0％；测试饲料为1％和3％）喂给了幼年的尼罗罗非鱼。将总共​​240条初始体重平均为3.5±0.02 g的鱼随机分为三组，每组重复四次，每重复20条。为了明显饱足，鱼在八周内每天喂两次。结果表明，所有治疗方法的生存率均无显着差异。与对照组相比，饲喂含1％酵母水解物的日粮的鱼的增重（WG），比生长速率（SGR），蛋白质效率比（PER）显着提高，而饲料转化率（FCR）较低。饲喂YH为1％和3％的鱼，肝脏中的谷胱甘肽过氧化物酶（GPx），超氧化物歧化酶（SOD），过氧化氢酶（CAT）活性较高，且丙二醛（MDA）含量明显低于对照组，表明抗肝功能增强-氧化剂状态。在添加了1％和3％酵母水解产物的饮食中，血清溶菌酶活性显着增加，表明对非特异性免疫反应的改善作用。在饲喂含1％YH的鱼中，IL-1β，IL-10，TNF-α，TGF-β2，ALP和TLR2的表达显着升高。结论，