亮氨酸与缬氨酸交互作用对刺参生长、体壁氨基酸组成及消化能力的影响

Effects of interaction of leucine and valine on growth, body wall amino acids composition, and digestive ability of sea cucumber Apostichopus japonicus

中文关键词: 刺参  亮氨酸  缬氨酸  生长  体壁氨基酸

英文关键词: Apostichopus japonicus  Leucine  Valine  Growth  Body wall amino acids

中文摘要:

      本实验旨在研究亮氨酸和缬氨酸的交互作用对刺参(Apostichopus japonicus)生长、体壁氨基酸组成及消化能力的影响。采用双因素实验(two-way ANOVA)设计，在基础饲料中分别添加0、1.06%、2.34%、3.40%的包膜亮氨酸和0、1.74%、2.50%、3.48%的包膜缬氨酸，配制成4个亮氨酸水平(实际含量为1.00%、1.50%、2.10%和2.60%) ×4个缬氨酸水平(实际含量为0.65%、1.40%、1.70%和2.20%)的16组等氮等脂的实验饲料，饲喂初始体重(16.80±0.18) g的刺参60 d。结果表明，亮氨酸和缬氨酸的含量及其交互作用显著影响了刺参的增重率和特定生长率。当饲料中缬氨酸含量为1.40%时，刺参体壁粗脂肪含量随着亮氨酸含量的升高而升高，二者之间存在协同作用，且L1.0V1.4组(亮氨酸1.00%，缬氨酸1.40%)显著低于其他组。亮氨酸和缬氨酸的交互作用显著影响了刺参体壁异亮氨酸、蛋氨酸、苯丙氨酸和酪氨酸的含量。当饲料中亮氨酸含量为2.10%时，随着缬氨酸含量的升高，肠道脂肪酶和淀粉酶的活性均先升高后降低，二者之间表现出先协同后拮抗的作用。淀粉酶活性在L2.6V1.4(亮氨酸2.60%，缬氨酸1.40%)组活性达到最大值，且显著高于其他各组。综上所述，亮氨酸和缬氨酸的含量及其交互作用显著影响了刺参的生长性能、体壁氨基酸组成及消化酶活力，以增重率为评价指标，刺参饲料中亮氨酸和缬氨酸的比值为1.90 (亮氨酸含量2.60%，缬氨酸含量1.40%)。

英文摘要:

      Branched chain amino acids (BCAAs) are neutral amino acids containing branched aliphatic chains on the α-carbon, including leucine (Leu), isoleucine, and valine (Val), accounting for 18%–20% of the total amino acids in animal and plant proteins. BCAAs are essential amino acids for animal growth; however, they cannot be synthesized in animals and can only be obtained from the diet. BCAAs participate in the metabolism of protein, fat, and carbohydrates; promote intestinal development and intestinal amino acid transport; and improve the immune capacity of the body. However, the imbalance of BCAAs in diets leads to poor growth and metabolic disorders in animals. BCAAs have similar chemical structures and catabolic pathways and compete for the same amino acid transporters when passing through cell membranes, resulting in antagonism. Sea cucumbers (Apostichopus japonicus) have rich nutritional value and are an important seafood source in northern China. In recent decades, the study of amino acid nutritional requirements of aquatic animals mainly focused on individual amino acid requirements, and few studies focused on the interaction between amino acids with strong correlations, particularly BCAAs. At present, the interaction of BCAAs has been studied in species such as Chinook salmon (Oncorhynchus tshawytscha), Rainbow trout (Oncorhynchus mykiss), Channel catfish (Ictalurus punctatus), Tilapia GIFT (Oreochromis niloticus), and Tiger puffer (Takifugu rubripes); however, the results have been inconsistent. The purpose of this experiment was to study the interaction effect of Leu and Val on the growth, body wall composition, and digestive ability of sea cucumbers. In this experiment, white fishmeal, algae powder, and wheat flour were used as the primary protein sources, and fish oil and soybean lecithin were used as the main lipid sources to design a basic diet with crude protein and lipid contents of 18.10% and 2.80%, respectively. In a two-way experimental design, 0%, 1.06%, 2.34%, and 3.40% coated Leu and 0%, 1.74%, 2.50%, and 3.48% coated Val were added to the basic feed. Sixteen groups of isonitrogen and isolipid diets were prepared with four Leu levels (actual content: 1.00%, 1.50%, 2.10%, and 2.60%) and four Val levels (actual content: 0.65%, 1.40%, 1.70%, and 2.20%). A total of 960 healthy sea cucumbers with an initial average weight of 16.80±0.18 g were selected and randomly assigned to 48 cylindrical circulating buckets. They were divided into 16 experimental groups, with three replicates in each group and 20 sea cucumbers in each replicate. The feeding period was 60 d. Bait was fed once a day at a fixed time (16:00). The water was changed every 2 d, and a siphon was used to withdraw the residual bait and feces from the bottom of the bucket. The amount of water changed was 50% of the water level in the bucket. During the breeding period, the water temperature was 14–17 ℃, pH was 7.4–8.2, and dissolved oxygen was at least 6 mg/L. A low-light environment was maintained indoors. The results showed that the Leu and Val contents and their interaction significantly affected the weight gain (WG) and specific growth rate of sea cucumbers. When the Val content was 1.4%, the crude lipid contents of the body wall increased with increasing dietary Leu contents, and there was a synergistic effect between Leu and Val; the L1.0V1.4 group was significantly lower than the other groups. The interaction between Leu and Val significantly affected the Val, Met, Tyr, and Phe contents in the body wall of sea cucumbers. When the Leu content was 2.1%, the intestinal lipase and amylase activities first increased and then decreased with increasing dietary Val contents; the interaction between Leu and Val showed a synergistic and then antagonistic effect. The amylase activity reached a maximum value in the L2.6V1.4 group and was significantly higher than that in other groups. In conclusion, Leu and Val contents and their interaction significantly affected the growth performance, body wall amino acid composition, and digestive ability of sea cucumbers. Taking WG as the evaluation index, the ratios of Leu and Val in sea cucumber feed were 1.90 (Leu content was 2.6%, Val content was 1.4%).