Gupta S K, Pal A K, Sahu N P, Dalvi R, Kumar V, Mukherjee S C
Department of Fish Nutrition and Biochemistry, Central Institute of Fisheries Education, Mumbai, India.
J Fish Dis. 2008 Sep;31(9):649-57. doi: 10.1111/j.1365-2761.2008.00939.x.
A 60-day feeding trial was conducted to study the immuno-protective effect of microbial levan on Labeo rohita juveniles challenged with Aeromonas hydrophila. Six purified diets were prepared with different levels of microbial levan: control (no levan), T1 (Basal + 0.25%), T2 (Basal + 0.50%), T3 (Basal + 0.75%), T4 (Basal + 1%) and T5 (Basal + 1.25%), fed to six groups of fish in triplicate. Among the treatment groups the haemoglobin content and total leucocyte count were increased with a dietary supplementation of levan at 1% or more. An increasing trend for total erythrocyte count was observed with increasing level of dietary levan. Lower levan-supplemented groups showed a higher albumin/globulin ratio. As the levan supplementation was increased, there was a gradual increase in serum lysozyme activity and respiratory burst activity [nitroblue tetrazolium (NBT) assay] reduction values. The highest lysozyme activity and NBT were observed in the T5 group although this was similar to the T4 group (P > 0.05). No significant histo-architectural changes were associated with dietary levan levels. After challenge with A. hydrophila, moderately degenerated hepatocytes, oedema and leucocytic infiltration in parenchymatous tissues, and extensive haemorrhage and haemosiderosis in the kidney were observed in the control group. However, the T5 group supplemented with 1.25% levan showed infiltrating leucocytes in the liver while the kidney showed only moderate degeneration of renal tubules. The relative survival per cent of juveniles after challenge with A. hydrophila was the highest in the T5 group followed by T4. This suggests that microbial levan at 1.25% can be used as dietary immunostimulant for L. rohita juveniles.
进行了一项为期60天的饲养试验,以研究微生物果聚糖对受嗜水气单胞菌攻击的露斯塔野鲮幼鱼的免疫保护作用。制备了六种含有不同水平微生物果聚糖的纯化日粮:对照组(无果聚糖)、T1(基础日粮+0.25%)、T2(基础日粮+0.50%)、T3(基础日粮+0.75%)、T4(基础日粮+1%)和T5(基础日粮+1.25%),以三组重复的方式投喂六组鱼。在各处理组中,日粮中添加1%或更多果聚糖时,血红蛋白含量和总白细胞计数增加。随着日粮果聚糖水平的增加,总红细胞计数呈上升趋势。添加较低果聚糖的组显示出较高的白蛋白/球蛋白比率。随着果聚糖添加量的增加,血清溶菌酶活性逐渐增加,呼吸爆发活性[硝基蓝四氮唑(NBT)试验]降低值逐渐增加。T5组观察到最高的溶菌酶活性和NBT,尽管这与T4组相似(P>0.05)。日粮果聚糖水平与组织学结构变化无显著关联。用嗜水气单胞菌攻击后,对照组观察到肝细胞中度退化、实质组织水肿和白细胞浸润,以及肾脏广泛出血和含铁血黄素沉着。然而,添加1.25%果聚糖的T5组肝脏中有白细胞浸润,而肾脏仅显示肾小管中度退化。用嗜水气单胞菌攻击后,幼鱼的相对存活率在T5组最高,其次是T4组。这表明1.25%的微生物果聚糖可作为露斯塔野鲮幼鱼的日粮免疫刺激剂。