GWT is an ingredient blend mixing vital wheat gluten,wheat flour and taurine with the ratio of 77.5％,20.5％,and 2.0％,respectively.This study was conducted to evaluate GWT as a protein source to compare with low-temperature dried fish meal (LT-FM) and soy protein concentrate (SPC) in extruded practical diet to feed to juvenile giant croaker (Nibea japonica) and black sea bream (Sparus macrocephalus).Plasma biochemical indices and liver anti-oxidative indices of the two fish species were tested as fish health indicators in this study.Eight diets had been formulated,including a control diet with LT-FM (20％) and SPC (21.4％),six diets with decreasing percentages of LT-FM or SPC replaced by GWT (replacing levels were 33.3％,66.7％ and 100％,respectively,on protein basis) and one diet with both 50％ of LT-FM and SPC was replaced by GWT.Each diet was fed to triplicate tanks of giant croaker with an initial weight of (12.83±0.91) g (26 fish per tank) and black sea bream with an initial weight of (15.40±0.02) g (35 fish per tank).All fish were reared in a sea-water flow-through system for 59 days.The results showed that there was no significant effect of replacing LT-FM by GWT on total protein (TP) content,plasma triglyceride (TC),and MDA content and liver SOD activity in giant croaker (P＞0.05).However,total cholesterol (TG) and glucose (GLU) contents in plasma were significantly decreased (P＜0.05),whereas the plasma SOD activity of juvenile giant croaker increased significantly (P＜0.05) when 66.7％ and 100％ of dietary LT-FM was replaced by GWT.Partial or total replacement of LT-FM or SPC by GWT had no significant effect on plasma levels of TP,TG,TC and GLU,liver MDA content and plasma SOD activity of black sea bream (P＞0.05).In contrast,significant increase of liver SOD activity was found when total LT-FM,33.3％ and 66.7％ of SPC,and 50％ of LT-FM and SPC in both were replaced by GWT in diet of black sea bream.To conclude,giant croaker was more sensitive than black sea bream to the significant reduction of LT-FM in the low fish meal based diet,with the changes of plasma biochemical indices and liver anti-oxidative indices.Highlights of the present study:firstly,it is the first study using GWT as main protein source in extruded diets for giant croaker and black sea bream;secondly,a low fishmeal (20％) containing extruded practical diet was used as the control.%本研究通过在低鱼粉型膨化饲料中添加不同比例的混合型小麦蛋白(GWT,由小麦蛋白、低筋面粉和牛磺酸分别以77.5％、20.5％和2.0％的比例混合而成),逐步替代饲料中低温干燥鱼粉(LT-FM)或大豆浓缩蛋白(SPC),饲喂日本黄姑鱼(Nibea japonica)[初始体重为(12.83±0.91)g]和黑鲷(Sparus macrocephalus)幼鱼[初始体重为(15.40±0.02)g]59 d,研究其对2种鱼类血清生化指标和肝脏抗氧化指标的影响.本研究配制8种等氮、等能饲料(粗蛋白:44.1％-45.6％、总能:21.5-22.0 MJ/kg),其中,对照组饲料以LT-FM(20.0％)和SPC(21.4％)为主蛋白源,6种实验饲料以GWT分别替代对照组饲料中33.3％、66.7％和100％的LT-FM或SPC蛋白,另配制1种实验饲料(联合替代组),用GWT替代对照组饲料中50％的LT-FM和SPC蛋白.结果显示,用GWT替代对照组饲料中的LT-FM对日本黄姑鱼血清总蛋白(TP)、甘油三酯(TG)和肝脏丙二醛(MDA)含量以及肝脏超氧化物歧化酶(SOD)活性均无显著影响(P＞0.05),但显著降低了血清总胆固醇(TC)、葡萄糖(GLU)含量(P＜0.05).相较对照组,GWT高比例(66.7％和100％)替代LT-FM引起日本黄姑鱼血清SOD活性的显著升高(P＜0.05).GWT替代对照组饲料中LT-FM或(和)SpC均未对黑鲷幼鱼血清中的TP、TG、TC、GLU含量、肝脏MDA含量和血清SOD活性产生显著影响(P＞0.05),而GWT完全替代LT-FM组、GWT替代33.3％和66.7％SPC组以及GWT联合替代组的黑鲷幼鱼肝脏SOD活性均显著上升(P＜0.05).总之,在本研究中,日本黄姑鱼相较黑鲷对低鱼粉饲料中鱼粉用量的进一步下降更为敏感,GWT高比例甚至完全替代LT-FM和SPC,未对黑鲷血清生化指标和肝脏抗氧化指标造成显著影响.本研究首次以小麦蛋白作为饲用蛋白源替代LT-FM和SPC在日本黄姑鱼和黑鲷中开展研究;实验采用低鱼粉型(20％)膨化实用饲料作为对照组.
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