蜡样芽孢杆菌YB1对大菱鲆幼鱼生长性能、肠道消化酶、肝脏抗氧化酶及肠道组织结构的影响

Effects of Bacillus cereus YB1 on Growth Performance, Intestinal Digestive Enzymes, Liver Antioxidant Enzymes, and Intestinal Tissue Structure of Juvenile Turbot (Scophthalmus maximus)

关键词:  蜡样芽孢杆菌  大菱鲆  酶活力  肠道组织结构  促生长

Key words:  Bacillus cereus  Scophthalmus maximus  Enzymatic activity  Intestinal tissue structure  Growth promotion

摘要:

为探究在饲料中添加蜡样芽胞杆菌(Bacillus cereus) YB1对大菱鲆(Scophthalmus maximus)幼鱼生长性能、肠道消化酶活力和肝脏抗氧化酶活力以及肠道组织结构的影响，本研究选取720尾初始体质量为(3.6±0.7) g的大菱鲆幼鱼，随机分为4组，每组3个平行，每个平行60尾。4组大菱鲆幼鱼在投喂的饲料中分别添加活菌量为0 (对照)、105、106和107 CFU/g的YB1，养殖期为50 d。结果显示，YB1添加量为107 CFU/g时，大菱鲆幼鱼的增重率(WGR)和特定生长率(SGR)显著高于对照组(P<0.05)。YB1添加量为106 CFU/g组的大菱鲆幼鱼肠道蛋白酶和淀粉酶活力分别提高了57.86%和82.37%，显著高于对照组(P<0.05)；YB1添加量提高到107 CFU/g时，脂肪酶的含量显著高于对照组(P<0.05)。饲料中添加YB1对大菱鲆幼鱼肝脏过氧化氢酶活力无显著性影响(P>0.05)；YB1添加量为106 CFU/g组的幼鱼肝脏丙二醛含量下降了42.03%，显著低于对照组(P<0.05)；实验组大菱鲆幼鱼肝脏超氧化物歧化酶活力相较于对照组有上升的趋势，差异不显著(P>0.05)。YB1添加量为106 CFU/g组的大菱鲆幼鱼肠道肌层厚度增加最为显著(P<0.05)，与对照组相比在实验末期提高了68.91%。研究表明，饲料中添加适量蜡样芽胞杆菌YB1具有促进大菱鲆幼鱼生长、提高幼鱼肠道消化酶和肝脏抗氧化酶活力以及改善幼鱼肠道组织结构的作用，推荐添加量为106 CFU/g。

Abstract:

Turbot (Scophthalmus maximus) is an economically important marine fish species in northern China. With the unceasingly amplification of farming scale and great improvement of intensivism in recent years, turbot diseases have been occurring frequently. Bacillus cereus YB1 could be used as a candidate probiotic strain, which has animal safety for turbot at a certain concentration. The present study aimed to investigate the effect of B. cereus (YB1) on growth performance, liver immune enzyme activity, intestinal digestive enzyme activity, and intestinal tissue structure of juvenile S. maximus, and would provide new probiotic strains for turbot aquaculture. A total of 720 healthy juveniles with an average body weight of (3.6±0.7) g were randomly divided into 4 groups with 3 replicates per group and 60 fish per replicate. The fish in the 4 groups were fed diets containing YB1 at a viable count of 0 (control), 105, 106, and 107 CFU/g at (21±2)℃, respectively, and the experiment lasted for 50 days. Results showed that the weight gain rate (WGR) and specific growth rate (SGR) were significantly higher in juvenile turbot fed diet supplemented with 107 CFU/g of YB1 than those of the fish fed the control diet (P<0.05). The amount of protease and amylase increased by 57.86% and 82.37%, respectively in 106 CFU/g group, and were significantly higher than those in the control group (P<0.05). Lipase content of fish in 107 CFU/g was significantly higher than that of the control group (P<0.05). Catalase activity in fish fed diets supplemented with YB1 was not significantly different from fish in the control group. Malondialdehyde content of juveniles fed 106 CFU/g YB1 dietary supplement was decreased by 42.03%, and was significantly lower than that in the control group (P<0.05). SOD activity of fish fed YBI increased compared with that of the control, however, the increase was not significant (P>0.05). YB1 led to a significant increase in the height and number of folds in the intestinal mucosa of turbot (P<0.05). Intestinal muscularis thickness was significantly increased in the 106 CFU/g YB1 dietary supplement group than in the control group; it was 68.91% higher than that of the control group at the end of the experiment. In this study, B. cereus (YB1) could promote the growth of juvenile turbot, improve the activities of digestive and liver immune enzymes in their intestine, and improve the structure of intestine. This study shows that B. cereus (YB1) can be used in turbot aquaculture, with a recommended dosage of 106 CFU/g.