Effects of bioflocs on growth performance, digestive enzyme activity and body composition of juvenile Litopenaeus vannamei in zero-water exchange tanks manipulating C/N ratio in feed
Effects of bioflocs on growth performance, digestive enzyme activity and body composition of juvenile Litopenaeus vannamei in zero-water exchange tanks manipulating C/N ratio in feed
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DOI：
10.1016/j.aquaculture.2012.05.022
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发表时间：
2012-08
期刊：
影响因子：
4.5
通讯作者：
Wujie Xu;L. Pan
中科院分区：
文献类型：
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作者：
Wujie Xu;L. Pan
本试验旨在研究促生菌对凡纳滨对虾幼鱼（平均6.95±0.22g）生长性能、饲料利用率、消化酶活性和全体组成的影响。对两种生物絮团处理和一种对照进行了评价：添加碳水化合物（CN15）和碳水化合物（CN20）的生物絮团池具有两种水平的C/N比（15,20），以及进行水交换而不添加碳水化合物（对照）的清水池。每组设4个重复池（125L），每个池装虾28只（相当于虾密度224只，生物量约1.56kg / m3水体积）。从一个室内生物絮体对虾养殖池中收集原始浓缩生物絮体，在放养对虾前以相同的量（0.5mLL−1个生物絮体体积）接种到所有生物絮体池中。在CN15和CN20处理池中，在添加35%粗蛋白质饲料的基础上，分别添加蔗糖作为碳水化合物来源，将输入饲料（饲料与蔗糖）的C/N分别提高至15和20，促进生物絮团的发育。水质参数监测结果表明，三组养殖对虾的水质参数均在推荐水平内。试验结束时，对虾成活率均在90%以上，3组间差异不显著（P < 0.05）；两种生物絮团处理对虾的生长（末重、增重和特定生长率）均显著优于对照组（P<0.05），饲料转化率显著低于对照组（P<0.05）。两种生物絮团处理对虾的蛋白酶和淀粉酶活性均有整体增强，但在不同消化组织（消化腺、胃和肠）中，生物絮团对每种酶活性的影响不一致。近似成分分析表明，两种生物絮凝剂处理对虾的粗脂肪和粗灰分含量均有增加的趋势。两种处理的生物絮凝体均表现出良好的营养价值和胞外酶活性。粗蛋白质和粗脂肪含量分别为27.3% ~ 31.6%和3.7% ~ 4.2%；蛋白酶和淀粉酶活性分别为10.7 ~ 14.4μmolmin−1g−1TSS和293.5 ~ 335.5μmolmin−1g−1TSS。本研究结果提示，促进型生物絮团可提高养殖对虾的生长性能和饲料利用率，可能是通过提供一种补充食物来源，提高饲料的消化和利用。
A 30-day feeding experiment was conducted to investigate the effects of promoted bioflocs on growth performance, feed utilization, digestive enzyme activity and whole body composition of Litopenaeus vannamei juveniles (average 6.95±0.22g) in zero-water exchange culture tanks. Two bioflocs treatments and one control were evaluated: Bioflocs-based tanks with two levels of C/N ratio (15, 20) by addition of carbohydrate referred to as ‘CN15’ and ‘CN20’, and clear water tanks operated with water exchange and without addition of carbohydrate referred to as ‘Control’. Each group consisted of quadruplicate tanks (125L) and each tank contained 28 shrimp (equivalent to shrimp density of 224 individuals and biomass of ~1.56kg per cubic meter of water volume). Original concentrated bioflocs were collected from an indoor bioflocs-based shrimp culture pond, and inoculated into all bioflocs-based tanks with the same amount (0.5mLL−1bioflocs volume) just before stocking shrimp. Sucrose was applied as a source of carbohydrate and added separately to the CN15 and CN20 treatment tanks in addition to the applied feed (35% crude protein), so as to raise the C/N ratio of the feeds input (feed and sucrose) to 15 and 20 and subsequently promote the development of bioflocs. The monitoring of water quality parameters showed that they all remained within recommended levels for shrimp culture in the three groups. At the end of the experiment, survival rates of the shrimp were above 90%, with no significant differences among the three groups (P>0.05); and the growth (in terms of final weight, weight gain and specific growth rate) of the shrimp in both bioflocs treatments were significantly better (P<0.05) than that obtained in the control while the feed conversion rate was significantly lower (P<0.05). An overall enhancement in protease and amylase activities of the shrimp in both bioflocs treatments was observed, though the effect of the bioflocs on each enzyme activity performed inconsistently among different digestive tissues: digestive gland, stomach and intestine. Proximate composition analysis showed that the crude lipid and ash contents of the shrimp in both bioflocs treatments tended to increase. The bioflocs collected from both bioflocs treatments showed good prime nutritional values and appropriate extracellular enzymes activities. The crude protein and crude lipid contents ranged from 27.3% to 31.6% and 3.7% to 4.2%, respectively; and protease and amylase activities ranged from 10.7 to 14.4μmolmin−1g−1TSS and 293.5 to 335.5μmolmin−1g−1TSS, respectively. The results from this study suggest that the promoted bioflocs can improve growth performance and feed utilization of the cultured shrimp, probably through providing a supplemental food source and enhancing feed digestion and utilization.