Department of Food Science and Technology, Sabzevar Branch, Islamic Azad University, Sabzevar, Islamic Republic of Iran.
Department of Aquatic Animal Health and Diseases, Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research Education and Extension Organization (AREEO), Tehran, Islamic Republic of Iran.
Fish Shellfish Immunol. 2017 Dec;71:230-238. doi: 10.1016/j.fsi.2017.10.016. Epub 2017 Oct 7.
The present study investigated the effects of dietary supplementation of stinging nettle (Urtica dioica) on growth performance, skin mucus, immune response and disease resistance of rainbow trout (Oncorhynchus mykiss) fed with diets supplemented with U. dioica at 0, 1, 2 and 3%. After 8 weeks of feeding, the addition of U. dioica at 3% level resulted in improved weight gain, specific growth rate and feed conversion ratio significantly when compared to the other groups (P < 0.05). Hematological responses including: hematocrit (Htc), hemoglobin (Hb), lymphocyte and neutrophil populations enhanced significantly in fish fed 3% of stinging nettle when measured after 4 weeks; while, total red blood cells, white blood, Htc, Hb, lymphocyte and neutrophil populations significantly increased after 8 weeks in the same group (P < 0.05). Total serum protein and glucose contents increased significantly in fish fed stinging nettle at 3% when compared to the other groups after 8 weeks; however, triglycerides decreased significantly in the same group on the 4th and 8th week (P < 0.05). Additionally, several immune parameters, namely, IgM, lysozyme, complement components C3 and C4, and respiratory burst of blood leukocytes significantly increased in the 3% fed group on the 4th week; while, after 8 weeks the immune responses enhanced in fish fed 2 and 3% diets (P < 0.05). At the end of the feeding trial, mucus samples obtained from the fish fed stinging nettle supplementation exhibited improved antagonistic activities against several bacterial pathogens (Streptococcus iniae, Yersinia ruckeri, Vibrio anguillarum and Lactococcus garviae), skin mucus enzymes activities (alkaline phosphatase, lysozyme, protease and esterase) and protein levels in 2 and 3% groups with the highest being in case of 3% group when compared to the other groups (P < 0.05). The cumulative mortality of rainbow trout subjected to Y. ruckeri infectious exhibited relatively low mortality levels in all supplemented groups with the lowest being in fish fed 3% stinging nettle. The present findings demonstrated that dietary administration of U. dioica enhanced growth and stimulated fish immunity; thus, enabling the fish to be more resistant against bacterial infections.
本研究调查了荨麻（荨麻）对虹鳟（Oncorhynchus mykiss）生长性能、皮肤黏液、免疫反应和抗病能力的影响，虹鳟饲料中添加了 0、1、2 和 3%的荨麻。8 周喂养后，与其他组相比，3%水平添加荨麻可显著提高增重率、特定生长率和饲料转化率（P<0.05）。血液学反应包括：在第 4 周测量时，血液比容（Htc）、血红蛋白（Hb）、淋巴细胞和中性粒细胞群在摄食 3%荨麻的鱼类中显著增强；然而，在同一组中，总红细胞、白细胞、Htc、Hb、淋巴细胞和中性粒细胞群在第 8 周显著增加（P<0.05）。与其他组相比，在第 8 周摄食荨麻的鱼类总血清蛋白和葡萄糖含量显著增加；然而，在同一组中，甘油三酯在第 4 和第 8 周显著降低（P<0.05）。此外，在第 4 周，3%喂养组的 IgM、溶菌酶、补体成分 C3 和 C4 以及血白细胞呼吸爆发等几种免疫参数显著增加；然而，在第 8 周，摄食 2%和 3%饮食的鱼类的免疫反应增强（P<0.05）。在喂养试验结束时，摄食荨麻补充剂的鱼类的黏液样本显示出对几种细菌病原体（鳗弧菌、迟缓爱德华氏菌、鳗弧菌和乳球菌）、皮肤黏液酶活性（碱性磷酸酶、溶菌酶、蛋白酶和酯酶）和蛋白质水平的拮抗活性提高，在 2%和 3%组中最高，在 3%组中最高与其他组相比（P<0.05）。感染迟缓爱德华氏菌的虹鳟的累积死亡率在所有补充组中均表现出相对较低的死亡率，在摄食 3%荨麻的鱼类中最低。本研究结果表明，日粮中添加荨麻可促进生长，刺激鱼类免疫力，从而使鱼类更能抵抗细菌感染。
