为研究发酵豆粕部分替代鱼粉后，饲料赖氨酸 (Lys) 水平对凡纳滨对虾生长、体组成与血清生化指标的影响，进而确定凡纳滨对虾对饲料赖氨酸的需要量，实验在基础饲料中分别添加0%、0.25%、0.50%、0.75%和1.00%的晶体赖氨酸配制成5种等氮等脂的实验饲料(含粗蛋白41.5%、粗脂肪7.5%)，实测各组赖氨酸含量分别为2.43%、2.65%、2.87%、3.06%和3.24%，记为Lys0、Lys25、Lys50、Lys75和Lys100。选择初始体质量为(2.0±0.1) g的凡纳滨对虾随机分为5组，每组3个重复，每个重复50尾虾，在室内水泥池中进行为期56 d的养殖实验。结果显示，随着饲料赖氨酸水平的提高，凡纳滨对虾的增重率 (WGR) 和特定生长率 (SGR) 先升高后降低，在Lys75组达到最高，且该组饲料系数 (FCR) 最低；凡纳滨对虾成活率不受饲料赖氨酸水平的影响。Lys75组对虾肌肉粗蛋白和粗脂肪含量最高，而对虾肌肉粗灰分和水分含量则不受饲料赖氨酸水平的影响；肌肉必需氨基酸中的赖氨酸、缬氨酸 (Val)、异亮氨酸 (Ile)、苯丙氨酸 (Phe) 随着饲料赖氨酸水平的提高呈先升高后降低的趋势。随着饲料赖氨酸水平的提高，血清中谷丙转氨酶 (ALT)、谷草转氨酶 (AST) 活性呈先升高后降低的趋势，甘油三酯 (TG) 含量呈逐渐升高的趋势，Lys75组超氧化物歧化酶 (SOD) 活性显著低于其他各组。对SGR、FCR与饲料赖氨酸水平进行二次曲线拟合分析，结果显示，凡纳滨对虾对赖氨酸的最适需求量分别为2.88%(饲料粗蛋白的6.94%)、2.89%(饲料粗蛋白的6.96%)。本实验通过探讨凡纳滨对虾在该饲料配方条件下对赖氨酸的最适需求量，旨在为其大规模配合饲料的生产提供参考。
The fish meal remains a high price with the worldwide shortage. Seeking different plant protein sources replacing fish meal to reduce the cost of feed has become one of the hotspots in shrimp nutrition research. However, most plant protein sources face the problem of amino acid imbalance after substituting fish meal, which affects the growth performance and feed utilization of the shrimps. Supplementing crystalline amino acids in feed is still the most effective and practical method to achieve amino acid balance of feeds. This study intended to explore the effects of different levels of lysine in feed on the growth performance, body composition and blood indices of Pacific white shrimp L. vannamei after replacing fish meal with fermented soybean meal at an optimal level, and to estimate the optimal dietary lysine requirement of juvenile L. vannamei. Five isonitrogenous and isolipidic practical diets(containing 41.5% crude protein and 7.5% crude lipid) were formulated with dietary supplemental lysine levels of 0%, 0.25%, 0.50%, 0.75% and 1.00%, and the measured values of dietary lysine contents were 2.43%, 2.65%, 2.87%, 3.06% and 3.24%, which were recorded as Lys0, Lys25, Lys50, Lys75 and Lys100. The L. vannamei with an average initial body weight about [(2.0±0.1) g] was randomly divided into 5 groups with 3 replicates per group and 50 shrimp per replicate. The feeding experiment lasted for 56 days in indoor cement pools. The results showed that, with the increase of feed lysine level, the weight gain rate and specific growth rate increased first and then decreased, reaching the highest in the Lys75 group with the lowest feed conversion ratio. The survival rate was not affected by feed lysine level. Muscle in Lys75 group had the highest crude protein and crude fat content, while crude ash and moisture content were not affected by feed lysine level. A variety of essential and non-essential amino acids in the muscle showed a trend of first increasing and then decreasing with the increase of feed lysine level. The turning point was in the Lys50 or Lys75 group. With the increase of feed lysine level, the activities of alanine aminotransferase and aspartate aminotransferase in serum increased first and then decreased, while the triglyceride content gradually increased, and the superoxide dismutase activity of Lys75 group was significantly lower than the other four groups. Based on the quadratic regression model of SGR and FCR with dietary lysine content, The optimal lysine requirements of L. vannamei were 2.88% (6.94% of dietary crude protein) and 2.89% (6.96% of dietary crude protein), respectively.