饲料中钾对皱纹盘鲍幼鲍生长及其生理指标的影响

EFFECTS OF DIETARY POTASSIUM ON GROWTH PERFORMANCE OF JUVENILE ABALONE (HALIOTIS DISCUS HANNAI INO) AND ITS PHYSIOLOGICAL RESPONSES

在以酪蛋白和明胶为蛋白源的半精制基础饲料中,添加不同浓度梯度的钾(0、2、4、8、16、32 g钾/kg饲料),钾源为KCl,配制成6种实验饲料(实测钾含量分别为:0.10、2.12、4.39、9.79、20.08和27.26 g/kg),探讨皱纹盘鲍(Haliotis discus hannai)幼鲍对饲料中钾的需求量及其在长期适应不同含量钾的过程中的生理反应。幼鲍初始体重为(0.24±0.00)g,初始壳长为(12.24±0.04)mm,实验在流水系统中进行,养殖周期为15周。实验期间水温12—23℃,海水钾含量为(472.94±3.59)mg/L。结果表明,饲料中不同含量的钾对皱纹盘鲍的增重率(WGR,%)、贝壳日增长(DISL,μm/d)及存活率没有显著影响(P>0.05)。皱纹盘鲍软体部的水分、粗脂肪和贝壳的灰分含量受饲料中钾含量的影响不显著(P>0.05)。当饲料中钾含量大于等于4.39 g/kg时,与0.10 g/kg饲料组相比,软体部粗蛋白质含量显著升高(P<0.05)。软体部钾的含量和贝壳中钾、钠的含量受饲料中钾含量的影响不显著(P>0.05)。幼鲍软体部钠含量在饲料钾含量为20.08、27.26 g/kg时显著低于其他各组(P<0.05)。鳃Na+-K+ATP酶活力随着饲料中钾含量的增加逐渐下降,当饲料中钾含量为20.08、27.26g/kg时,与0.10 g/kg组相比显著降低(P<0.05),但与其他组相比差异不显著。因此研究认为:以生长指标为判据,不需要在饲料中补充钾,海水中钾和饲料原料中的钾能够维持皱纹盘鲍幼鲍的正常生长;但以生理指标(软体部粗蛋白质和钠含量,鳃Na+-K+ATP酶活力)评判,饲料中钾的适宜含量为2.12 g/kg。

A 15-week feeding trial was conducted to study the effects of dietary potassium on growth and physiological responses of juvenile abalone, Italiotis discus hannai Ino. Six casein-gelatin based semi-purified diets containing graded levels of dietary potassium （KC1, 0.10, 2.12, 4.39, 9.79, 20.08 and 27.26 g/kg dry diet, respectively） were fed to juvenile abalone [initial weight： （0.24 ± 0.00） g; initial shell length： （12.24 ±0.04） ram] in triplicate groups in a flow-through system. During the experimental period, the water temperature ranged from 12 to 23 ℃ and potassium concentration was （472.94 ± 3.59） mg/L in the seawater. The results showed that there were no significant （P 〉 0.05） differences in the weight gain ratio （WGR, %）, daily increment in shell length （DISL, gin/d） and the survival of abalone among treatments. There were also no significant （P 〉 0.05） differences in lipid, moisture contents in soft body and ash content in shell among the six dietary treatments. Compared with that in the treatment of 0.10 g/kg diet, the protein content in soft body increased significantly （P 〈 0.05） when dietary potassium was more than 4.39 g/kg diet. The content of potassium in the soft body and potassium, sodium in the shell was maintained relatively constant regardless of dietary treatment. The soft body sodium content was significantly （P 〈 0.05） lower in 20.08 and 27.26 g/kg of dietary treatment than any other treatments. The activity of gill Na＋-K＋ ATPase decreased steadily with the increasing of dietary potassium. Data from the growth parameters （WGR and DISL） showed that it was unnecessary to add potassium to the diets, and the potassium from diet sources and seawater was sufficient for the optimal growth of juvenile abalone. Based on the physical index （protein and sodium contents in soft body and Na＋-K＋ ATPase activity in gill）, the optimal concentration of dietary po tassium was 2.12 g/kg.