投喂频率对绿鳍马面鲀幼鱼生长、生理指标及肝脏hsp70基因表达丰度的影响

Effects of feeding frequency on the growth, physiology, and expression abundance of hsp70 mRNA in juvenile Thamnaconus septentrionalis

中文关键词: 投喂频率  绿鳍马面鲀  生长性能  生理指标

英文关键词: Feeding frequency  Thamnaconus septentrionalis  Growth performance  Physiological index

中文摘要:

      为探究投喂频率对绿鳍马面鲀(Thamnaconus septentrionalis)幼鱼生长、生理指标及肝脏hsp70基因表达的影响，本研究设5个投喂频率，分别为1、2、3、4和5次/d (分别简称为F1、F2、F3、F4和F5)，每个处理组设3个平行，每缸养殖30尾鱼[(6.47±0.56) g]。实验期间，水温为17℃~ 26℃，盐度为30~31，pH为6.8~7.6，溶解氧≥5 mg/L，养殖周期为30 d。结果表明，不同投喂频率对绿鳍马面鲀幼鱼的生长、体成分、消化酶和抗氧化酶活性均有影响。随着投喂频率的增加，绿鳍马面鲀幼鱼的摄食和生长均呈上升趋势，F5组数值最大，摄食率为3.95%，增重率为347.19%，特定生长率为5.07%/d，增重率为F1组的2倍多。F1组的肥满度为1.79，显著低于其他4组(P<0.05)；肝体比逐渐升高，F4和F5组的肝体比显著高于其他3组(P<0.05)。增加投喂频率，鱼体的粗蛋白含量呈先升高后降低的趋势，F2组最高，为59.82%；粗脂肪含量呈逐渐升高的趋势，F5组最高，为31.23%。胰蛋白酶活性随投喂频率增加呈先降低后增加的趋势，F3组活性最低，为37.48 U/μg prot；脂肪酶活性逐渐升高，F5组最高，为2.67 U/g prot；淀粉酶活性不受投喂频率的影响(P>0.05)。过氧化氢酶、超氧化物歧化酶活性和丙二醛含量最高均在F5组，分别为14.71 U/mg prot、250.32 U/mg prot和2.73 nmol/mg。肝脏中hsp70基因的相对表达量不受投喂频率的影响(P>0.05)。基于绿鳍马面鲀幼鱼的生长性能和生理效应的综合考虑，其最适投喂频率为3次/d。

英文摘要:

      The effects of five different feeding frequencies on the growth performance, physiological index, and hepatic heat shock protein 70 (hsp70) gene expression levels of juvenile Thamnaconus septentrionalis [body weight of (6.47±0.56) g] were studied. The experiment design included 5 feeding frequencies, namely 1, 2, 3, 4, and 5 times/d (referred to as F1, F2, F3, F4, and F5 respectively), and each treatment group was designed with 3 parallels, and each tank was cultured 30 fish. The experimental period was 30 days and water temperature range was 17℃~26℃, the salinity was 30~31, the pH was 6.8~7.6, and the dissolved oxygen was ≥ 5 mg/L. Results showed that under different feeding frequency conditions, the growth, body composition, digestive enzymes, and antioxidant enzyme activities of the juvenile T. septentrionalis were affected. With the increase in feeding frequency, the feeding and growth of T. septentrionalis showed an upward trend. The F5 group had the largest value, with a feeding rate of 3.95%, a weight gain rate of 347.19%, a specific growth rate of 5.07%/d. The weight gain rate of the F5 group exceeded twice the value of the F1 group. The condition factor of the F1 group was 1.79, which was significantly lower than that of the other four groups (P<0.05). The hepatosomatic index gradually increased, and the F4 and F5 groups exhibiting significantly higher values than the other three groups (P<0.05). With an increase in the feeding frequency, the crude protein content of the experimental fish showed a trend of first increasing and then decreasing: F2 showed the highest crude protein content of 59.82%, and the crude lipid content showed a gradually increasing trend: F5 was the highest with a crude lipid content of 31.23%. Trypsin activity showed a trend of first decreasing and then increasing with the increase in feeding frequency. The F3 group had the lowest activity of 37.48 U/μg prot; lipase activity gradually increased, and the F5 group showed the highest activity of 2.67 U/g prot; amylase activity was not affected by the feeding frequency (P>0.05). Catalase activity, superoxide dismutase activity, and the content of malondialdehyde were the highest in the F5 group, at 14.71 U/mg prot, 250.32 U/mg prot, and 2.73 nmol/mg, respectively. The relative expression levels of the hsp70 gene in the liver was not affected by the feeding frequency (P>0.05). Based the findings of this study and the comprehensive consideration of the growth performance and physiological indices of Thamnaconus septentrionalis, the optimal feeding frequency for this species was determined to be 3 times/d.