Evaluation of floating cages as an experimental tool for marine shrimp culture studies under practical earthen pond conditions

The New Caledonia blue shrimp Litopenaeus stylirostris is commercially produced under semi-intensive rearing conditions. The size of the farming earthen ponds (5–10 ha) and the subsequent production constraints make it difficult to use them as experimental units for random experiments. Moreover, since every pond has its own characteristics, ponds' effects cannot be ruled out, thus making it hard to define true replicates.In order to design future experiments under conditions resembling those used in production, we evaluated the possible use of floating cages as experimental units with the aim of assessing treatment effects with a reasonable statistical power. To this end, two sets of floating cages were placed respectively in two different ponds in a commercial farm. In both cases the zootechnical conditions in the cages were similar in post-larvae origin, management, and diet and feeding regime.The aim of the study was to evaluate on a technical basis the possibility of rearing shrimps in floating cages set up in earthen ponds and to assess this method from a statistical standpoint. Shrimps reared in and outside the cages showed comparable growth and survival rates. The variability in the zootechnical parameters between cages, expressed as the estimated coefficient of variation (CV) for survival rate, total final biomass (g), final body weight (g), daily increment in body weight (g day^− 1) and FCR were 11.0, 13.7, 4.4, 5.4, and 7.0%, respectively. On the basis of these figures, we calculated for a given statistical power (80%) the number of replicates (cages) that would be required to reveal significant differences between two treatments, at a 5% level of significance. We found that for expected differences of 20% from the control mean, 3 and 6 floating cages per treatment would be reasonable to determine statistical differences for growth parameters and survival rate, respectively. Moreover, we showed a significant pond effect in regard to survival and growth between the two sets of cages. These results illustrated the within-farm variability among the ponds, and confirmed that the specific characteristics of each pond from the same farm make it difficult to use the ponds themselves as experimental units.The study demonstrates that rearing in floating cages is an economical, powerful and sensitive experimental tool for shrimp culture studies specifically carried out under conditions close to semi-intensive production.     

Effects of Echerichia coli lipopolysaccharides and dissolved ammonia on immune response in southern white shrimp Litopenaeus schmitti

The success of penaeid shrimp aquaculture has been limited by endemic and epidemic infectious diseases around the world and shrimp defense mechanisms are a priority for control, prevention, and diagnosis. The lethal dose (LD₅₀) of Escherichia coli lipopolysaccharides was calculated and pathogen injection and dissolved ammonia concentration on immune response were evaluated in southern white shrimp Litopenaeus schmitti. The lethal dose of lipopolysacharides was 3.78 mg kg^− 1 body weight. Injection caused changes in phenoloxidase activity in plasma and nitric oxide and total haemocyte counts within the first 24 h. High concentration of dissolved ammonia caused a decrease in haemocytes by 66% within the first 72 h, when compared to the control. Hemagglutination in plasma was not affected by injection or high concentrations of dissolved ammonia. The results showed that white shrimp recognized the lipopolysacharides and responded to this microbial elicitor, as indicated by a variety of immunological indicators and that increased dissolved ammonia affected the number of circulating haemocytes.     

Effects of dietary Bacillus and medicinal herbs on the growth, digestive enzyme activity, and serum biochemical parameters of the shrimp Litopenaeus vannamei

White shrimp (Litopenaeus vannamei) was fed six different formulations of medicinal herbs (MH) and Bacillus in a feeding trial conducted for 56 days. The survival, growth, digestive enzyme activity, and serum biochemical parameters were assessed. A basal diet without MH and Bacillus was served as the control. At the end of feeding trial, survival ranged from 76.19% to 84.76% with no significant differences (P > 0.05) among all groups. Growth measured as final weight, specific growth rate (SGR), protein efficiency ratio (PER), protein productive value (PPV), and feed efficiency ratio (FER) were improved with increased dietary MH and Bacillus. Shrimp fed 0.2% MH and 0.3% Bacillus (Diet 23) were found to have the best growth performance. For shrimp fed Diet 23 final weight and SGR were significantly (P < 0.05) higher than for controls. The digestive enzyme activity of protease and amylase in hepatopancreas and intestines were significantly (P < 0.05) enhanced by the feed supplements, however amylase of the hepatopancreas was not affected. Serum protein and glucose content were enhanced by the supplement of MH and Bacillus. Serum cholesterol in shrimp of high Bacillus level groups was significantly (P < 0.05) higher than in the control group. However, no significant difference (P > 0.05) in serum Triacylglycerols between supplemented groups and control was found. Results revealed that the combined MH and Bacillus in diet could enhance growth because it can improve digestive enzyme activity and digestive metabolism.     

2种水产杀虫剂共同使用对南美白对虾的急性毒性试验

通过试验验证在水体中先后施用不同溶度的杀虫剂（阿维菌素和辛硫磷）在48小时内导致南美白对虾的中毒情况和死亡率。2种药物混合使用对南美白对虾的最低致死浓度范围：阿维菌素1．5～2．25×10^-4mg/L＋辛硫磷1．2-1．8×10^-2mgm,不同浓度的杀虫剂对南美白对虾的致死时间随着浓度的增加而缩短。南美白对虾对阿维菌素中毒症状表现为麻痹、昏迷、死亡,辛硫磷中毒症状表现为抽搐、痉挛、死亡。     

内陆碱性水域凡纳滨对虾生长与环境因子的关系

研究内陆碱性水域凡纳滨对虾体重生长速度分别与碱度、盐度、pH、离子系数、Ca2 、Mg2 、K 质量浓度、Ca2 Mg2 以及(1/2Ca2 )/(1/2Mg2 )、Na /K 等水环境因子的相关性。结果表明,这些因子对对虾体重生长速度的影响存在相互作用;它们与体重生长速度的简单相关性都受到其他因子的显著负效应影响;碱度、盐度、pH、离子系数、Ca2 Mg2 、(1/2Ca2 )/(1/2Mg2 )及Ca2 质量浓度对对虾生长的影响被弱化;Mg2 质量浓度的影响不明显。内陆碱性水域K 质量浓度和Na /K 很可能是影响对虾生长的主要环境因子;适当提高盐度及Ca2 、K 质量浓度,降低Na /K ,将有利于对虾生长。     

壳聚糖硫酸酯提高凡纳滨对虾抗白斑综合征病毒感染力的研究

论述如下一项研究,采用壳聚糖硫酸酯添加到饲料中投喂凡纳滨对虾,4周后检测对虾血清酚氧化酶、超氧化物歧化酶和溶菌酶活性;同时进行白斑综合征病毒(WSSV)的肌肉注射感染实验,以检测壳聚糖硫酸酯对病毒的抗感染能力。实验结果显示,饲料中壳聚糖硫酸酯添加量为0.15‰和0.50‰,能显著提高凡纳滨对虾血清酚氧化酶活性;添加量为0.15‰时,能显著提高对虾血清超氧化物歧化酶活性,但添加量继续增大时反而下降;在低添加量时,对虾血清溶菌酶活性与对照组相近,添加量为0.15‰和0.50‰时,对虾血清溶菌酶活性随添加量增大而升高。凡纳滨对虾摄食添加壳聚糖硫酸酯饲料4周后,经注射WSSV攻毒感染,壳聚糖硫酸酯添加量为0.04‰、0.15‰和0.50‰试验组,对虾比成活率分别为39.3%、42.9%和53.6%,而未摄食壳聚糖硫酸酯的对照组成活率仅为17.9%。结果表明,摄食壳聚糖硫酸酯可以明显提高对虾抵御WSSV感染的能力。     

海藻糖对南美白对虾免疫活性物的影响

以南美白对虾为实验对象,将海藻糖作为免疫诱导制剂,注射到南美白对虾体内,在连续注射5d和7 d时,分别对南美白对虾血清中的凝血活性、超氧化物歧化酶活性(SOD)、溶血素活性进行测定。结果表明,注射海藻糖5 d和7 d时,南美白对虾血清中凝集活性比对照组分别提高了3倍、2倍,SOD比对照组分别提高了2.5倍、2倍,溶血素活性比对照组分别提高了2倍、1.5倍。说明海藻糖可以明显提高南美白对虾血清中这3种酶的表达水平。     

饲料中添加谷胱甘肽对凡纳滨对虾肝胰腺抗氧化指标和脂质过氧化物含量的影响

采用1种对照饲料和5种添加不同水平还原型谷胱甘肽（GSH）（添加量分别为60、120、180、240和300 mg·kg-1）的试验饲料,饲喂初始体重约为1.12 g的凡纳滨对虾（Litopenaeus vannamei）,分别命名为G0、G60、G120、G180、G240和G300组,经8周饲养后,观察饲料中不同浓度的GSH对凡纳滨对虾生长性能、肝胰腺抗氧化指标和脂质过氧化物含量的影响。结果表明,南美白对虾的增重率随着饲料中GSH添加量的增加而增加,在G180组达到高峰,但随着GSH添加量的进一步增加,增重率呈下降趋势（P<0.05）;饲料转化率随饲料中GSH添加量的升高而显著升高,在G240组达到最高（P<0.05）;成活率随饲料中GSH添加量的增加而显著提高,提高幅度为8.53%~31.69%。饲料中添加GSH能不同程度地提高凡纳滨对虾肝胰腺中抗氧化酶活力（P<0.05）,其中G60、G120组的谷胱甘肽还原酶,G120、G180和G300组的超氧化物歧化酶,G120、G180和G240组的谷胱甘肽过氧化物酶活力,分别显著高于对照组G0（P<0.05）。各试验组肝胰腺中GSH含量和总抗氧化能力比对照组G0分别提高了8.93%~52.57%和3.02%~37.03%,且呈剂量――效应关系。对虾肝胰腺中的活性氧含量随着日粮中GSH添加量的增加呈现下降的趋势,其中G180、G240组显著低于对照组（P<0.05）;与对照组相比,试验各组肝胰腺丙二醛含量显著降低（P<0.05）,抗O2-能力升高,在G120、G180、G240和G300组达到显著水平（P<0.05）。研究结果初步表明,饲料中添加一定量的GSH能提高凡纳滨对虾生长性能和肝胰腺抗氧化能力并降低脂质过氧化物含量。表4参18     

微生态净水剂对凡纳滨对虾生理生化指标的影响

为了证实微生态净水剂(含菌量10×109/g)可以提高虾体免疫力和对污染物(如农药)的抵抗力,在凡纳滨对虾(Litopenaeus vannmei)养殖过程中,设置了施用微生态净水剂的实验组和未用微生态净水剂的对照组,采用肌肉注射的方式,对2组凡纳滨对虾进行乙酰甲胺磷毒性实验。注射乙酰甲胺磷后,采样测定血细胞吞噬化学发光情况,组织中超氧化物歧化酶(SOD)、过氧化物酶(POD)、溶菌酶(LSZ)、酯酶活性以及酯酶(EST)、苹果酸脱氢酶(MDH)同工酶表型变化。结果表明:施用微生态净水剂组明显好于对照组。施用微生态净水剂的虾注射乙酰甲胺磷后死亡率降低,血细胞的吞噬功能也有所增加,虾体组织内SOD、POD、LSZ、酯酶活性变化较未用组的虾变化幅度较小,其中,SOD、POD活性等高于未用组,EST、MDH同工酶酶带数目也有增加。说明微生态净水剂从本质上增强虾体内代谢、提高虾体的免疫力、增强其对外界环境变化适应能力,并具有提高虾体防御功能,增强抵抗疾病能力的作用。     

藻—溞系统对凡纳滨对虾养殖水体调控效果的研究

取5000 mL灭菌后的凡纳滨对虾养殖尾水于5000 mL高压灭菌的烧杯中,分为10组,分别为蛋白核小球藻组(C1)、蛋白核小球藻+大型溞组(C2)、衣藻组(C3)、衣藻+大型溞组(C4)、隐藻组(C5)、隐藻+大型溞组(C6)、蛋白核小球藻+衣藻组(C7)、蛋白核小球藻+衣藻+大型溞组(C8)、衣藻+隐藻组(C9)、...