饲料中维生素A水平对凡纳滨对虾生长、饲料利用、体组成成分及非特异性免疫反应的影响

本文旨在研究5种等氮等能饲料中,维生素A添加水平对凡纳滨对虾(Penaeus vannameiBoone)生长、饲料利用、体组成成分及非特异性免疫反应的影响。试验选用平均初始体重为(0.069±0.005)g的凡纳滨对虾450尾,随机分为5个处理组,每组90尾,每组设3个重复,每个重复30尾。试验采用单因素设计,以维生素A醋酸酯为维生素A源,用添加不同水平维生素A(添加量分别为0、18、365、4和72 mg/kg)的饲料喂养凡纳滨对虾,试验期11周。结果表明:在养殖前4周,饲料中添加维生素A显著促进凡纳滨对虾的生长(P<0.05),提高其对饲料利用效率(P<0.05),而对对虾的成活率不产生显著的影响(P>0.05);第11周的结果表明,饲料中添加维生素A并不能显著影响凡纳滨对虾的生长、饲料利用效率和成活率(P>0.05)。维生素A对对虾体脂肪、蛋白质含量的影响显著(P<0.05),对对虾体水分和灰分含量无显著影响(P>0.05)。维生素A对对虾血清中溶菌酶活力、酚氧化酶活力和血液红细胞数量的影响显著(P<0.05),饲料中未添加维生素A或过量添加(超过36 mg/kg)均导致血清中溶菌酶活力、酚氧化酶活力和血细胞总数显著下降(P<0.0 5),而对血清超氧化物歧化酶活力无显著影响(P>0.0 5)。用折线回归模型分析饲料维生素A添加量与对虾增重率的变化关系,表明在试验前4周,凡纳滨对虾饲料中维生素A的适宜添加量为2 2.5 0 mg/kg;1 1周试验期间,凡纳滨对虾饲料中维生素A适宜添加量为1 8 mg/kg;以溶菌酶、酚氧化酶活力为指标,凡纳滨对虾饲料中维生素A最适添加量为5 9.5 1 mg/kg。

Effects of Dietary Vitamin A Levels on Growth, Feed Utilization, Body Composition and Non-specific Immunological Responses of Juvenile Shrimp

To study the effects of different dietary levels of vitamin A on growth performance,feed utilization,body composition and non-specific immunological responses of juvenile shrimp(Penaeus vannamei Boone),an experiment was conducted using a total of 450 juvenile shrimps to investigate the effects of adding vitamin A(0,18,36,54 and 72 mg/kg respectively) on growth,feed utilization,body composition and non-specific immunological responses of juvenile shrimp(Penaeus vannamei Boone).Juvenile shrimps were randomly divided into 5 treatments with 3 replicates each(90 for each treatment,30 for each replicate).Five iso-nitrogenous and iso-energies diets were formulated as experimental diets,and the experiment lasted for 11 weeks.The results showed: In 4-week feeding trial,the diet with vitamin A supplementation could significantly increase the growth rate,feed convention ratio(FCR) and protein efficiency ratio(PER) of juvenile shrimp(P<0.05),While the survival rate was not affected(P>0.05).Up to 11-week feeding trial,there was no significant effect of increasing dietary vitamin A on growth,the survival rate,FCR and PER of shrimp(P>0.05).The whole body lipid and protein content were significantly affected by the dietary vitamin A supplementation levels(P<0.05),while there was no significant effect of vitamin A on body moisture and ash content.The activity of superoxide dismutase(SOD) of shrimp serum was not affected by the dietary vitamin A levels(P>0.05).The phenoloxidase activity,lysozyme activity and red blood count decreased significantly when the dietary without vitamin A supplementation or more than 36 mg/kg were supplemented(P<0.05).Based on broken-line regression analysis of weight gain rate at 4 wk and 11 wk,lysozyme activity and phenoloxidase activity(at 11wk),the optimal dietary supplementation levels of vitamin A for this diet formulation was 22.5 mg/kg,18.0 mg/kg and 59.51 mg/kg,respectively.