In the present study, we aimed to evaluate the effects of dietary thymol on growth, antioxidant status, liver health, immune response and disease resistance of snakehead fish (Channa argus) (initial weight, 11.86 ± 0.15 g). The fish were fed for 56 days with a basal diet supplemented with thymol at 0, 150, 300, 450, 600 and 750 mg/kg, leading to six experimental diets. The final body weight (FBW), weight gain (WG), protein efficiency ratio (PER) and specific growth rate (SGR) were increased as dietary thymol level increased, arriving a summit value at 450 mg/kg dietary thymol level, and then, values of these indices started to decrease when dietary thymol level further rose, and feed conversion ratio (FCR) is the opposite state. Our results showed a significant increase (p < .05) in the superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH‐Px) activities in liver, spleen, head kidney and intestine with diets supplemented with 300 and 450 mg/kg thymol compared to the control and significantly decrease (p < .05) in the malondialdehyde (MDA) activity. Results showed that dietary supplementation with 300 and 450 mg/kg thymol significantly increased (p < .05) the serum acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LZM) activities and immunoglobulin M (IgM), complement 3 (C3), complement 4 (C4) concentrations of C. argus compared to the control, and decreased (p < .05) the serum glutamic‐pyruvic transaminase (ALT) and glutamic‐oxaloacetic transaminase (AST) activities. Moreover, the expression of HSP70, TNF‐α, IL‐1β and IL‐8 were down‐regulated in liver, head kidney and intestine by dietary supplementation with 300 and 450 mg/kg thymol, and the expression of IL‐10 and TGF‐β was up‐regulated. After challenge with Aeromonas veronii, survival rates in all thymol treatment groups were significantly increased (p < .05). Consequently, our results indicate that adequate dietary supplementation thymol can effectively enhance the growth, antioxidant status, immune response and disease resistance of C. argus, and the optimum dietary thymol requirement for maximum WG of C. argus was estimated to be 356 mg/kg.

中文翻译：

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香椿日粮中最佳百里酚需求量：对生长，抗氧化能力，免疫反应和抗病性的影响

在本研究中，我们旨在评估日粮百里酚对蛇头鱼（Channa argus）（初始重量，11.86±0.15 g）的生长，抗氧化剂状态，肝脏健康，免疫应答和抗病性的影响。用补充了百里酚的基础饮食以0、150、300、450、600和750 mg / kg的饲料喂养鱼类56天，从而产生了六种实验性饮食。随着饮食百里酚水平的增加，最终体重（FBW），体重增加（WG），蛋白质效率比（PER）和比生长率（SGR）均增加，达到450 mg / kg饮食百里酚水平的最高值，然后，当膳食百里酚水平进一步上升时，这些指数的值开始下降，而饲料转化率（FCR）处于相反状态。我们的结果显示显着增加（p 补充了300和450 mg / kg百里香酚的饮食，肝脏，脾脏，头部肾脏和肠道中的超氧化物歧化酶（SOD），过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GSH-Px）活性低于<.05） 丙二醛（MDA）活性显着降低（p <.05）。结果表明，膳食补充300和450 mg / kg百里酚可显着提高（p  <.05）血清酸性磷酸酶（ACP），碱性磷酸酶（AKP），溶菌酶（LZM）活性和免疫球蛋白M（IgM），补体3（ C3），补体4（C4）浓度的阿古斯。与对照组相比，并降低了（p <.05）血清谷氨酸丙酮酸转氨酶（ALT）和谷氨酸草酰乙酸转氨酶（AST）活性。此外，通过补充300和450 mg / kg百里酚酚，肝，头肾和肠中HSP70，TNF-α，IL-1β和IL-8的表达下调，IL-10和TGF的表达也被下调。-β上调。与挑战后气单胞菌维罗纳，在所有百里香酚治疗组存活率显著上升（p <.05）。因此，我们的结果表明有足够的膳食补充百里酚可有效增强生长，抗氧化状态，免疫应答和抗病性乌鳢，而对于最大WG适宜日粮麝香草酚要求乌鳢估计为356毫克/千克。