The use of terrestrial raw materials to replace fish meal (FM) and fish oil (FO) in marine fish diets may affect fish growth performance and health. In the last years functional additives have been profiled as good candidates to reduce the effects on health and disease resistance derived from this replacement, via reinforcement of the fish immune system. In the present study, three isoenergetic and isonitrogenous diets with low FM and FO (10% and 6% respectively) were tested based on supplementation either with 0.5% galactomannanoligosaccharides (GMOS diet) or 0.02% of a mixture of essential oils (PHYTO diet), a non-supplemented diet was defined as a control diet. Fish were fed the experimental diets in triplicate for 9 weeks and then they were subjected to a stress by confinement as a single challenge (C treatment) or combined with an experimental intestinal infection with Vibrio anguillarum (CI treatment). Along the challenge test, selected stress and immunological parameters were evaluated at 2, 24 and 168h after C or CI challenges. As stress indicators, circulating plasma cortisol and glucose concentrations were analyzed as well as the relative gene expression of cyp11b hydroxylase, hypoxia inducible factor, steroidogenic acute regulatory protein, heat shock protein 70 and heat shock protein 90 (cyp11b, hif-1α, StAR, hsp70 and hsp90). As immune markers, serum and skin mucus lysozyme, bactericidal and peroxidase activities were measured, as well as gene expression of Caspase-3 (casp-3) and interleukin 1β (il-1ß).

The use of functional additives induced a significant (p < 0.05) reduction of circulating plasma cortisol concentration when confinement was the unique challenge test applied. Supplementation of PHYTO induced a down-regulation of cyp11b, hif-1α, casp-3 and il-1β gene expression 2h after stress test, whereas StAR expression was significantly (p < 0.05) up-regulated. However, when combination of confinement stress and infection was applied (CI treatment), the use of PHYTO significantly (p < 0.05) down-regulated StAR and casp-3 gene expression 2h after challenge test, denoting that PHYTO diet reinforced fish capacity of stress response via protection of head kidney leucocytes from stress-related apoptotic processes, with lower caspase-3 gene expression and a higher il-1β gene expression when an infection occurs. Additionally, dietary supplementation with GMOS and PHYTO compounds increased fish serum lysozyme after infection. Both functional additives entailed a better capability of the animals to cope with infection in European sea bass when fed low FM and FO diets.

在海鱼饲料中使用陆地原料代替鱼粉（FM）和鱼油（FO）可能会影响鱼类的生长性能和健康。在最近几年中，功能性添加剂被认为是通过增强鱼类免疫系统来降低这种替代品对健康和抗病性的影响的良好候选物。在本研究中，通过补充0.5％的半乳甘露寡糖（GMOS饮食）或0.02％的精油混合物（PHYTO饮食），测试了三种低FM和FO（分别为10％和6％）的同能饮食和等氮饮食。 ，将非补充饮食定义为对照饮食。鳗弧菌（CI治疗）。沿着攻击测试，在C或CI攻击后的2、24和168h评估选定的压力和免疫学参数。作为应激指标，分析了血浆血浆皮质醇和葡萄糖浓度以及cyp11b羟化酶，缺氧诱导因子，类固醇生成的急性调节蛋白，热休克蛋白70和热休克蛋白90（cyp11b，hif-1α，StAR， hsp70和hsp90）。作为免疫标记，测量了血清和皮肤粘液溶菌酶，杀菌和过氧化物酶活性，以及​​Caspase-3（casp-3）和白介素1β（il-1ß）的基因表达。

当限制是唯一的挑战性试验时，使用功能性添加剂可显着降低（p <0.05）循环血浆皮质醇浓度。压力试验后2h，补充PHYTO会引起cyp11b，hif-1α，casp-3和il - 1β基因表达下调，而StAR表达则显着上调（p <0.05）。但是，当应用限制压力和感染相结合（CI治疗）时，PHYTO的使用显着（p <0.05）下调了StAR和casp-3攻击试验后2h的基因表达，表明PHYTO饮食通过保护头部肾脏白细胞免受应激相关的凋亡过程增强了鱼的应激反应能力，当感染发生时caspase-3基因表达较低，il-1β基因表达较高。此外，在感染后，膳食中添加GMOS和PHYTO化合物可增加鱼血清溶菌酶。当饲喂低FM和FO饮食时，两种功能性添加剂都使动物具有更好的能力应对欧洲鲈鱼的感染。