A 56 days feeding trial was conducted to investigate the effects of enzyme-treated soy protein (ETSP) supplementation in low protein diets on immune function of immune organs (head kidney, spleen and skin) in on-growing grass carp. A total of 540 on-growing grass carp (initial average weight: 325.72 ± 0.60 g) were fed six diets, which included a normal protein diet (28% crude protein) and five low protein diets (26% crude protein) supplemented with graded levels of ETSP (0.0, 0.8, 1.2, 1.6 and 2.0%). At the end of feeding period, a challenge test was performed by infection with Aeromonas hydrophila for two weeks. The results indicated that (1) reducing dietary protein content from 28 to 26% decreased antibacterial substances and aggravated inflammatory responses of above three immune organs; (2) under the condition of reducing protein level in diet, 0.8–1.2% ETSP supplementation reversed these above adverse effects on immune function of above three immune organs; (3) suitable ETSP supplementation-decreased inflammatory responses were partly associated with [IκB kinase β (IKKβ)/inhibitor of κBα (IκBα)/nuclear factor kappa B (NF-κB) p65 and p52 or NF-κB p65] signaling and [target of rapamycin (TOR)/(S6K1, 4E-BP)] signaling in above three immune organs. (4) On the basis of C3 content (head kidney), C4 content (spleen) and skin hemorrhage and lesion, the optimal ETSP supplementation levels in low protein diets were estimated to be 1.48%, 1.61% and 1.03%, respectively. In summary, ETSP supplementation in low protein diets improved immune function of head kidney, spleen and skin in on-growing grass carp.

进行了为期56天的喂养试验，以研究低蛋白饮食中添加酶处理的大豆蛋白（ETSP）对生长中草鱼免疫器官（头肾，脾脏和皮肤）免疫功能的影响。总共给540只生长中的草鱼（平均平均重量：325.72±0.60 g）饲喂六种日粮，其中包括普通蛋白日粮（28％粗蛋白）和五种低蛋白日粮（26％粗蛋白），并添加了分级饲料。 ETSP水平（0.0、0.8、1.2、1.6和2.0％）。在喂养期结束时，通过嗜水气单胞菌感染进行了攻击试验两个星期。结果表明：（1）饮食蛋白质含量从28％降低到26％，上述三种免疫器官的抗菌物质减少，炎症反应加剧；（2）在饮食中降低蛋白质水平的情况下，添加0.8–1.2％的ETSP可逆转上述对三个以上免疫器官免疫功能的不利影响；（3）适当的ETSP补充降低的炎症反应部分与[IκB激酶β（IKKβ）/κBα抑制剂（IκBα）/核因子κB（NF-κB）p65和p52或NF-κBp65]相关，并与[上述三个免疫器官中雷帕霉素（TOR）/（S6K1，4E-BP）的信号通路] （4）根据C3含量（头肾），C4含量（脾脏）以及皮肤出血和病变，低蛋白饮食的最佳ETSP补充水平估计为1.48％，1。分别为61％和1.03％。总之，在低蛋白饮食中补充ETSP可改善生长中草鱼的头肾，脾脏和皮肤的免疫功能。