【摘要】 幼建鲤体重(11 37±0 55)g,投喂不添加或添加维生素A的3组试验饲料,进行饲养实验70d,攻毒实验15d和免疫接种实验24d,研究维生素A缺乏对幼建鲤生长性能和免疫功能的影响,结果表明,维生素A缺乏组(0IU/kg)建鲤的成活率、摄食量、增重、净蛋白质沉积率、肥满度、肝胰脏指数、肝胰脏维生素A含量、肠道皱襞高度,头肾重量、脾脏重量和指数、后肾重量和指数、血液红细胞、白细胞数量和血清溶菌酶活力显著降低(P<0 05),且饲料系数显著增加(P<0 05),而对头肾体指数、用灭活嗜水气单胞菌免疫后第10和17天血清抗体水平影响不显著(P>0 05)。基于本实验研究结果,可知维生素A是维持幼建鲤正常生长和免疫机能必不可少的营养成分。当饲料中维生素A含量达到3969IU/kg时,一定程度上可满足幼建鲤正常生长和免疫机能的需要,进一步提高饲料维生素A含量(达23816IU/kg),对幼建鲤生长和饲料利用没有显著影响,但在一定程度可提高其免疫机能。更多还原

【Abstract】 Jian carp（Cyprinus carpio var.Jian）was a new variety with fast growth,efficient feed conversion,strong disease resistance,high market value,and excellent hereditary properties,and considered as a commercially important teleost for inland culture in China.The objective of the study was to determine the effect of dietary vitamin A deficiency on growth performance and immune responses of juvenile Jian carp cultured in nine indoor glass tanks （80cm×55cm×30cm）.Three isonitrogenous （350.2g/kg diet） and isolipidic （48.9g/kg diet） practical diets were formulated to contain graded levels of dietary vitamin A （0,3969 and 23816IU vitamin A/kg diet,respectively） at the cost of wheat flour.They were randomly fed to triplicate groups,each 40 fish with initial body weight （11.37±0.55）g for 70d in a flow-through tap water system maintained at 21℃with continuous aeration.A 15-day challenge trial and a 24-day vaccination trial were undertaken at the termination of the growth trial,respectively.The challenge trial was done by intraperitoneal （i.p.） injection of Aeromonas hydrophila at a concentration of 0.5 mL/ind(LD（50） around 10¹⁰ CFU/ind).The control group （non-infective group） was injected i.p.with 0.5 mL 0.9% NaCl/ind.The vaccination trial was conducted by i.p.injection of formalinkilled bacterins of A.hydrophila.The control fish were injected with an equal volume of sterile phosphate buffered saline （pH 7.4,PBS）.Growth performance,feed utilization,morphometry,haematology,lysozyme activity and antibody levels at days 0,10,17 and 24 after i.p.injection of formalin-killed A.hydrophila were determined for the fish species at the end of these trials.The results showed that Jian carp fed vitamin A-free diet possessed the significantly lowest survival rate,weight gain,feed intake,protein retention ratio （PRR）,condition factor （CF）,hepatopancreas somatic index （HSI）,hepatopancreas vitamin A content （HVA）,intestinal fold height （fold heights of anterior and posterior intestines,respectively）,head kidney weight,spleen body index （SBI）,post kidney weight,post kidney body index （PKBI）,blood erythrocyte and leukocyte counts,survival and serum lysozyme activity after challenge with A.hydrophila （P<0.05）.Furthermore,the fish fed vitamin A-free diet showed markedly high feed conversion ratio （FCR） （P<0.05）,but head kidney body index （HKBI） and serum antibody levels at days 0,10 and 17 （AB（0）,AB（10） and AB（17）,respectively） after vaccination with formalin-killed A.hydrophila showed no marked discrepancies among the three treatments （P>0.05）.AB（24）（antibody level at day 24） was the lowest （P<0.05） for fish fed vitamin A-free diet but showed no significant differences for fish fed diet with 3969IU vitamin A/kg diet （P>0.05）.Increasing dietary vitamin A content from （3969IU/kg） to 23816IU/kg did not have statistically marked effect on growth performance and feed utilization of Jian carp（P>0.05）,but significantly improved hepatopancreas vitamin A content,intestinal fold heights,post kidney weight,blood leucocyte counts,lysozyme activity and AB（24） （P<0.05）.Based on these observations,adequate dietary vitamin A content （3969IU/kg） had positive effects on growth performance,feed utilization and immune responses of juvenile Jian carp,but dietary vitamin A content increasing from 3969IU/kg to 23816IU/kg didn’t significantly improve growth performance or feed utilization,but partially increased the ability of immune responses of juvenile Jian carp in resistance against （A.hydrophila.）更多还原