维生素A对青鱼幼鱼生长、代谢、抗氧化能力和免疫能力的影响

Effects of Vitamin A on Growth,Metabolism,Antioxidant Capacity and Immunity of Juvenile Black Carp( Mylopharyngodon piceus)

本研究以青鱼幼鱼为试验对象,探讨6种不同维生素A含量(290、1 033、1 734、3 835、7 662和14 943 IU/kg)的等氮等能饲料对青鱼幼鱼生长、代谢、抗氧化能力和免疫能力的影响。选取540尾初始体重为(5.35±0.16)g的青鱼幼鱼,随机分为6组,每组饲喂1种饲粮,每组3个重复,每个重复30尾。试验期60 d。结果表明:1)随着饲料中维生素A含量的增加,增重率、特定生长率、蛋白质效率都呈现先升高后下降的趋势,并在维生素A含量在3 835 IU/kg时达到最高。折线模型分析结果显示,饲料中维生素A含量在2 246.64 IU/kg时,能够获得最大增重率。2)饲料中维生素A含量从290 IU/kg增加到7 662 IU/kg,肝脏中的α淀粉酶、胰蛋白酶、糜蛋白酶和弹性蛋白酶活性显著增加(P<0.05),肝脏中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPX)、谷胱甘肽还原酶(GR)活性和总抗氧化力(T-AOC)也呈现显著上调(P<0.05);肝脏中谷胱苷肽转移酶(GST)活性和丙二醛(MDA)含量随着维生素A含量的增加均呈现先降低后升高的趋势,并均在3 835 IU/kg组达到最低值。3)与290 IU/kg组相比,3 835和7 662 IU/kg组血清中溶菌酶(LYZ)活性、补体3(C3)和补体4(C4)含量显著提高(P<0.05);饲料中适量的维生素A(1 734、3 835和7 662 IU/kg)能够显著提高血细胞中LYZ、干扰素α(INFα)、铁调素(HEPC)、天然抗性相关巨噬蛋白(NRA MP)、C3和补体9(C9)基因表达量(P<0.05)。因此,在饲料中添加适量维生素A不仅能够促进青鱼幼鱼的生长和代谢,还能增强其抗氧化和非特异性免疫能力;以增重率为判据,青鱼幼鱼饲料中维生素A适宜含量为2 246.64 IU/kg。

The present trial was conducted to determine the effects of diets with six vitamin A contents(290,1 033,1 734,3 835,7 662 and 14 943 IU/kg)on growth,metabolism,antioxidant capacity and immunity of juvenile black carp(Mylopharyngodon piceus).A total of 540 juvenile black carps with initial body weight of(5.35±0.16)g were divided into six groups,and carps in each were fed one of the six diets.Each group had 3 replicates with 30 carps per replicate.The experiment lasted for 60 days.The results showed as follows:with the increase of dietary vitamin A content,weight gain rate(WGR),specific growth rate(SGR)and protein efficiency ratio(PER)firstly increased and then decreased,and reached to the highest when dietary vitamin A was 3 835 IU/kg.Based on the broken-line regression analysis for WGR,the optimal content of dietary vitamin A was 2 246.64 IU/kg for the maximal WGR.2)When dietary vitamin A content was increased from 290 to 7 662 IU/kg,the activities ofαamylase,trypsin,chymotrypsin,elastase in liver were significantly increased(P<0.05),similarly,the activities of superoxide dismutase(SOD),catalase(CAT),glutathione peroxidase(GPx)and glutathione reductase(GR),and total antioxidant capacities(T-AOC)in liver were also significantly up-regulated(P<0.05).The activities of glutathione-S-transferase(GST)and content of malondialdehyde(MDA)were firstly decreased and reached to the lowest level when dietary vitamin A was 3 835 IU/kg,and then increased.3)Compared with 290 IU/kg group,the activity of lysozyme(LYZ)and contents of complement 3(C3)and complement 4(C4)in serum of in 3 835 and 7 662 IU/kg groups were significantly increased(P<0.05).Proper contents of dietary vitamin A(1 734,3 835 and 7 662 IU/kg)could also significantly up-regulate the gene expression levels of LYZ,interferonα(IFNα),hepcidin(HEPC),natural resistance-associated macrophage protein(NRAMP),C3 and complement 9(C9)in blood cell(P<0.05).Therefore,adequate dietary vitamin A can significantly increase growth performances,improve metabolic abilities and then enhance non-specific immunity in juvenile black carp;according to the WGR,the optimal vitamin A content in diets for juvenile black carp is 2 246.64 IU/kg.