微颗粒饲料与冰冻桡足类对大黄鱼稚鱼生长、存活和体成分的影响

摘要

评估三种新开发的微颗粒饲料(Diet 1,Diet 2和Diet 3)、一种混合饲料(Diet 4:Diet 3和冰冻桡足类混合投喂)和冰冻桡足类(Diet 5)对25-60日龄大黄鱼稚鱼的饲喂效果.Diet 1组大黄鱼稚鱼的特定生长率(SGR,7.97％/d)和成活率(40.0％)最高,而Diet 5组稚鱼的SGR(4.15％/d)和成活率(20.4％)最低.Diet4组稚鱼的成活率与Diet 1组差异不显著,但其SGR低于后者.从稚鱼的SGR和成活率看,三种微颗粒饲料中,Diet 1要优于Diet 2和Diet 3.各处理组中每桶稚鱼的生物量与SGR有相似的变化趋势.各微颗粒饲料组稚鱼的体蛋白含量差异不显著,低于Diet 4组,但高于Diet 5组.而微颗粒饲料组稚鱼的脂肪含量(10.6％-13.3％)均显著高于Diet 4组(7.6％)和Diet5组(7.2％).尽管冷冻桡足类中C20:4n-6(AA)的含量稍低于微颗粒饲料,但Diet4和Diet 5组稚鱼的AA含量均显著高于微颗粒饲料组.Diet 4和Diet 5组稚鱼的C22:6n-3(DHA)分别高于其相应饲料中的含量.相反地,微颗粒饲料组稚鱼的C20:5n-3(EPA)低于微颗粒饲料中的含量.这些结果表明,Diet 4和Diet 5组稚鱼体内AA、DHA和EPA的沉积效率高于微颗粒饲料组.研究表明,大黄鱼稚鱼可用微颗粒饲料“断奶”.基于Diet 1优于Diet 2和Diet 3,可将其作为进一步研究的基础配方.此外,有必要对各处理组大黄鱼稚鱼消化酶和消化道的变化进行研究以综合评估微颗粒饲料的效果.%Three newly developed microdiets (MDs:Diet 1,Diet 2 and Diet 3),one co-feeding diet (Diet 4,combined Diet 3 with frozen copepods) and frozen copepods (Diet 5) were tested for weaning large yellow croaker (Pseudosciaena crocea) larvae from 25 to 60 days after hatching (DAH).The highest final specific growth rate (SGR,7.97％/d) and survival (40.0％) were observed in fish fed Diet I,while those were the lowest in fish fed Diet 5 (4.15％/d and 20.4％,respectively).The survival of larvae fed Diet 4 showed no significant difference (P＞0.05) from that of larvae fed Diet 1.However,SGR of larvae fed Diet 4 was significantly lower (P＜0.05) than that of larvae fed Diet 1.Among the MDs,Diet I was proved to be superior to Diet 2 and Diet 3 for both SGR and survival.For all treatments,biomass in each tank was observed a similar trend as SGR.Whole-body protein was not significantly different (P＞0.05) among fish fed the MDs,which was lower than that of fish fed Diet 4,but higher than that of fish fed Diet 5.Fish fed the MDs had significantly higher (P＜0.05) lipid deposition (10.6％-13.3％) than fish fed either Diet 4 (7.6％) or Diet 5 (7.2％).Dietary C20:4n-6 (AA) level was significantly lower (P＜0.05) in Diet 5 than that in the MDs.However,the AA level was significantly higher (P＜0.05) in fish fed either Diet 4 or Diet 5 than that in fish fed the MDs.The exceeded C22:6n-3 (DHA)levels in fish compared to their corresponding diets were found in those fed either Diet 4 or Diet 5.Inversely,C20:5n-3(EPA) and DHA levels decreased in fish fed the MDs relative to their proportions in MDs.These results showed that fish fed either Diet 4 or Diet 5 had higher efficiency ofAA,DHA and EPA deposition than fish fed the MDs.This study suggested that large yellow croaker larvae could be successfully weaned by MD.Future research should be based on formula of Diet 1,since it was superior to Diet 2 and Diet 3.In addition,changes of digestive enzymes and digestive tract of large yellow croaker larvae fed different diets need to be investigated for an overall evaluation.