Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway.
Laboratory of Immunology, Centre of Aquatic Biotechnology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago, Chile.
Front Immunol. 2021 Feb 25;12:599530. doi: 10.3389/fimmu.2021.599530. eCollection 2021.
The present study investigated effects of dietary inclusion of black soldier fly larvae (BSFL) () meal and paste on gut health, plasma biochemical parameters, immune response and skin mucus proteome in pre-smolt Atlantic salmon (). The seven-week experiment consisted of seven experimental diets: a control diet based on fishmeal and plant protein (Control-1); three BSFL meal diets, substituting 6.25% (6.25IM), 12.5% (12.5IM) and 25% (25IM) of protein; two BSFL paste diets, substituting 3.7% (3.7IP) and 6.7% (6.7IP) of protein and an extra control diet with 0.88% of formic acid (Control-2). The 6.25IM diet reduced enterocyte steatosis in pyloric caeca, improved distal intestine histology, and reduced IgM in distal intestine. The fish fed 12.5IM diet reduced enterocyte steatosis in pyloric caeca, improved distal intestine histology, had a higher plasma lysozyme content compared to 6.25IM, and tend to increase phagocytic activity in head-kidney macrophages-like cells. On the other hand, 25IM diet improved distal intestine histology, but showed mild-moderate enterocyte steatosis in pyloric caeca, increased IFNγ and reduced IgM in distal intestine. In the case of BSFL paste diets, 3.7IP diet caused mild inflammatory changes in distal intestine, although it reduced enterocyte steatosis in pyloric caeca. The 6.7IP diet reduced enterocyte steatosis in pyloric caeca and improved distal intestine histology. Increasing level of BSFL meal in the diet linearly decreased plasma C-reactive protein, whereas increasing level of BSFL paste linearly increased plasma antioxidant capacity. Dietary inclusion of BSFL meal and paste had minor effects on the expression profile of proteins in skin mucus and no effects on immune markers in splenocytes. BSFL meal showed no negative effect on liver and muscle health as indicated by plasma alanine aminotranseferase, asparate aminotransferase and creatine kinase. The present study showed that replacing conventional protein sources with low to moderate levels of BSFL meal (6.25% and 12.5%) or paste (3.7% and 6.7%) reduced enterocyte steatosis in pyloric caeca, while replacing up to 25% with BSFL meal or 6.7% with paste improved distal intestine histology. Further, dietary inclusion of BSFL meal and paste had minor effects on skin mucus proteome and immune response in Atlantic salmon.
本研究探讨了在大西洋鲑（）幼鱼期饲料中添加黑蝇幼虫（）粉和浆对肠道健康、血浆生化参数、免疫反应和皮肤黏液蛋白质组的影响。为期七周的实验包括七种实验饲料：一种基于鱼粉和植物蛋白的对照饲料（对照-1）；三种黑蝇幼虫粉饲料，分别替代 6.25%（6.25IM）、12.5%（12.5IM）和 25%（25IM）的蛋白质；两种黑蝇幼虫浆饲料，分别替代 3.7%（3.7IP）和 6.7%（6.7IP）的蛋白质和一种额外的对照饲料，其中含有 0.88%的甲酸（对照-2）。6.25IM 饲料可减少幽门盲囊的肠细胞脂肪变性，改善远端肠道组织学，并降低远端肠道中的 IgM。12.5IM 饲料组可减少幽门盲囊的肠细胞脂肪变性，改善远端肠道组织学，与 6.25IM 相比，血浆溶菌酶含量更高，并可增加头肾巨噬细胞样细胞的吞噬活性。另一方面，25IM 饲料可改善远端肠道组织学，但幽门盲囊的肠细胞脂肪变性轻微至中度，且远端肠道的 IFNγ 增加，IgM 减少。在黑蝇幼虫浆饲料的情况下，3.7IP 饲料可引起远端肠道的轻度炎症变化，尽管它可减少幽门盲囊的肠细胞脂肪变性。6.7IP 饲料可减少幽门盲囊的肠细胞脂肪变性并改善远端肠道组织学。随着饲料中黑蝇幼虫粉水平的线性增加，血浆 C 反应蛋白水平线性降低，而黑蝇幼虫浆水平的线性增加则增加了血浆抗氧化能力。饲料中添加黑蝇幼虫粉和浆对皮肤黏液中的蛋白质表达谱几乎没有影响，对脾细胞中的免疫标志物也没有影响。黑蝇幼虫粉对肝脏和肌肉健康没有负面影响，表现为血浆丙氨酸氨基转移酶、天冬氨酸氨基转移酶和肌酸激酶正常。本研究表明，用低至中等水平的黑蝇幼虫粉（6.25%和 12.5%）或浆（3.7%和 6.7%）替代传统蛋白源可减少幽门盲囊的肠细胞脂肪变性，而用黑蝇幼虫粉替代高达 25%或用黑蝇幼虫浆替代 6.7%可改善远端肠道组织学。此外，饲料中添加黑蝇幼虫粉和浆对大西洋鲑的皮肤黏液蛋白质组和免疫反应几乎没有影响。
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