凡纳滨对虾幼虾的缬氨酸需要量

Valine Requirement of Juvenile Pacific White Shrimp,Litopenaeus vanname

通过8周的饲养试验评估饲料中缬氨酸含量对凡纳滨对虾(Litopenaeus vannamei)幼虾生长性能、常规营养组成、氨基酸代谢酶活性的影响,以确定凡纳滨对虾幼虾的缬氨酸需要量。以鱼粉、豆粕作为主要蛋白质源配制6种等氮等能(粗蛋白质含量约为40.0%,粗脂肪含量约为7.5%)的试验饲料,其实测缬氨酸含量(干物质基础)分别为1.56%、1.64%、1.72%、1.82%、1.90%、1.96%。选择体重在0.3 g左右的凡纳滨对虾幼虾540尾,随机分为6组,每组(饲料)3个重复,每个重复30尾。结果表明:增重率、特定生长率、蛋白质沉积率和饲料效率均随着饲料中缬氨酸含量的增加先升高后降低,并均在缬氨酸含量为1.82%时达到最大。全虾中粗蛋白质含量在缬氨酸含量为1.72%时达到最高,进一步提高饲料中缬氨酸含量则有不同程度降低;肌肉中粗蛋白质含量在缬氨酸含量为1.96%时达到最高,显著高于缬氨酸含量为1.56%和1.72%时(P<0.05);饲料中缬氨酸含量对全虾和肌肉中水分、粗脂肪和粗灰分含量的影响均不显著(P>0.05)。血清和肝胰脏中最高丙氨酸转氨酶活力均出现在缬氨酸含量最高组(缬氨酸含量为1.96%的组),而肌肉中最高丙氨酸转氨酶活力出现在缬氨酸含量为1.90%的组,且肝胰腺中碱性磷酸酶的活力也在缬氨酸含量为1.90%时达到最高;饲料中缬氨酸含量对肝胰腺中天冬氨酸转氨酶活力未产生显著影响(P>0.05)。以增重率为判定指标,通过折线模型得到凡纳滨对虾幼虾的缬氨酸需要量为占饲料干物质的1.79%(占饲料蛋白质的4.48%),考虑到晶体氨基酸在海水中的溶失,以缬氨酸在海水中浸泡30 min内的溶失率为16.81%计,核定凡纳滨对虾幼虾的缬氨酸需要量为占饲料干物质的1.53%(占饲料蛋白质的3.83%)。

An 8-week feeding trial was conducted to study the effect of dietary valine content on growth per-formance, common nutrient composition and amino acid metabolic enzyme activities of juvenile Pacific white shrimp （ Litopenaeus vanname ） , and in order to determine the valine requirementof juvenile Pacific white shrimp. Six isonitrogenous and isoenergetic experimental diets （ crude protein content was about 40.0%, and crude lipid content was about 7. 5%） were formulated with fish meal and soybean meal as main protein sources,and the measued values of valine content （ dry matter basis） in those diets were 1. 56%, 1.64%, 1.72%, 1.82%, 1.90% and 1.96%, respectively. A total of 540 juvenile Pacific white shrimp with the body weight was about 0.3 g were randomly divided into 6 groups with 3 replicates per group （ diet） and 30 juven-iles per replicate. The results showed that the weight gain rate, specific growth rate, protein retention rate and feed efficiency were firstly increased and then decreased with dietary valine content increasing, and the biggest values of them were found when dietary valine content was 1.82%. When dietary valine content was 1.72%, the crude protein content of whole body had the highest value, and it was decreased in different degree with di-etary valine content further increasing. The crude protein content of muscle had the highest value when dietary valine content was 1. 96%, and it was significantly higher than when dietary valine content was 1. 56% or 1.72% （ P〈0.05） . However, the contents of moisture, crude lipid and ash of whole body and muscle were not significantly affected by dietary valine content （ P〉0.05） . The highest values of alanine aminotransferase activ-ity in serum and hepatopancreas were all found in the group with the highest content of valine （ the group with the valine content was 1.96%） , and the highest values of alanine aminotransferase activity in muscle and alka-line phosphatase activity in hepatopancreas were all found in the group with the valine content was 1.90%. Di-etary valine content had no significant effect on aspartate aminotransferase activity in hepatopancreas （ P〉0.05） . With the weight gain rate as an evaluation index, broken-line model analysis results show that the valine requirement of juvenile Pacific white shrimp is 1.79% of dietary dry matter （4.48% of dietary protein）. Con-sidering the leaching loss of crystalline amine acid in seawater, make the valine dissolve-loss rate of diet im-mersed in seawater within 30 min is 16. 81%, the determined valine requirement of juvenile Pacific white shrimp is 1.53% of dietary dry matter （3.83% of dietary protein）.