The effects of density and artificial substrate on intensive shrimp Litopenaeus vannamei nursery production     

《Aquacultural Engineering》2020

Recirculating aquaculture systems (RAS) can be installed indoors, allowing year-round production of tropical animals in nearly any climate. A nursery phase is commonly used in Litopenaeus vannamei production since it allows for enhanced biosecurity and better quantification of animals while reducing space requirements. However, it is unclear whether animal density and inclusion of artificial substrate may improve shrimp performance during the nursery phase. In this experiment, we compared shrimp production parameters in two stocking densities with or without the use of an artificial substrate by creating four treatments: low-density LD; 1500 PL/m⁻³, low-density with substrate LDS, high-density HD; 3000 PL/m⁻³), and high-density with substrate (HDS). The LDS and HDS treatments included 0.46-m² of high-density polyethylene 2.5-cm mesh as a substrate, which increased the tank surface area by 21 %. Each treatment was randomly assigned to four 160-l culture tanks, each with a biofilter. The shrimp had an initial weight of 4 mg and were grown for 50 days. The low-density treatments had significantly higher dissolved oxygen (DO) and pH than the high-density treatments (P ≤ 0.001). Specifically, LDS had the highest DO and pH followed by the LD, HD, and HDS treatments, respectively. High-density treatments had significantly higher NO₂-N levels than low-density treatments during week 2 of the experiment when an unusually high concentration of nitrite was observed. FCR was significantly lower in both low-density treatments than in high-density treatments. At harvest, the total biomass (kg m⁻³) was significantly higher in high-density treatments than in low-density treatments (P ≤ 0.001), and the HDS treatment had a significantly greater biomass output than HD. Producers should consider artificial substrate and higher densities during nursery production to maximize shrimp production; however, the effects on water quality should also be taken into account.  相似文献   

东北梅花鹿茸不同部位水解氨基酸含量的比较分析   总被引：2，自引：1，他引：1  

王艳梅  邹兴淮 《经济动物学报》2003,7(4):18-21

对 10支东北梅花鹿茸作了不同部位水解氨基酸含量的比较分析 ,结果表明 ,水解氨基酸含量在东北梅花鹿茸腊片、粉片、血片和骨片各部位之间差异极显著 (P <0 0 1)。  相似文献   

东北地区春玉米临界氮浓度稀释曲线的建立和验证   总被引：3，自引：0，他引：3  

卢宪菊  郭新宇  温维亮  于泽涛 《中国农业科技导报》2019,21(11):77-83

过量施氮是目前玉米栽培中存在的普遍现象,基于临界氮浓度稀释曲线计算得出的氮营养指数是诊断氮营养丰缺的重要手段。基于东北地区4个生态点的试验数据,构建了东北地区春玉米临界氮稀释曲线,并在此基础上建立了氮营养指数模型和需氮量模型,结果表明,东北地区春玉米地上部临界氮浓度与生物量符合幂函数关系。利用独立试验资料对建立的临界氮浓度稀释曲线进行检验,发现基于临界氮浓度稀释模型计算的氮营养指数可以准确诊断玉米植株的氮营养状况,并计算出实时的氮素需求量。该研究建立的东北地区春玉米临界氮稀释模型可以为该地区春玉米的氮营养诊断和动态调控提供较好的理论和技术指导。  相似文献   

Use of Porcine Meal in Plant‐based Practical Diets for Pacific White Shrimp,Litopenaeus vannamei          下载免费PDF全文

Xuan Qiu  D. Allen Davis 《Journal of the World Aquaculture Society》2018,49(3):582-589

Two growth trials were conducted to evaluate and confirm the efficacy of a porcine meal (PM) with high protein content (>90%) as an alternative feed ingredient in commercial‐type feed formulation for Pacific white shrimp, Litopenaeus vannamei. Six experimental diets were formulated for the two growth trials. The first five diets contained increasing levels (0, 1, 2, 4, and 6%) of PM as a replacement for soybean meal in a plant‐based diet with low inclusion level (6%) of fish meal (FM). The last experimental diet was produced utilizing 4.2% PM to completely replace FM. In Trial 1, shrimp (1.5 g initial mean weight, 20 shrimp/tank, n = 4) were offered test diets for 6 wk in a semirecirculation system. At the end of Trial 1, shrimp fed with the diet containing 6% PM exhibited significantly enhanced weight gain (WG), feed conversion ratio (FCR), and survival compared to those fed with the diet devoid of FM. As survival was poor across all treatments and different densities could mask growth results the trial was repeated. In Trial 2, shrimp (0.85 g, 15 shrimp/tank, n = 4) were offered diets for 6 wk. Dietary supplementation of PM at 6% significantly improved WG, FCR, and apparent net protein retention in contrast with the treatment devoid of FM, confirming the same trends in Trial 1. No significant difference was detected in protein, lipid, moisture, and mineral profiles of whole‐body shrimp as well as survival across all the treatments. Results of this study indicate that PM is a good high protein source in shrimp feeds, which can be included up to 6% in the low FM‐based diet without compromising the growth of shrimp.  相似文献   

辽宁省普惠金融发展的问题与对策探讨     

信钰  刘莹 《辽宁农业职业技术学院学报》2020,22(3):62-64

振兴东北老工业基地的一条重要路径是促进普惠金融发展。普惠金融的重点服务对象需要有政府的介入与协调以及资金和政策的支持。根据辽宁省普惠金融发展现状的调查,本文通过研究,发现在辽宁普惠金融发展过程中存在一系列的问题,并给出相应的政策建议。  相似文献   

东北地区农机制造业的地位和作用及发展措施     

迟宏伟  李智  金风华 《农机化研究》2007,(1):4-8

农业装备是农业现代化的重要物质基础,是提高农业生产效率、保障资源充分与有效利用和环境友好与可持续发展的有效工具,是用工业化和信息化改造传统农业的有效载体,是装备"三农"的战略产业,对保障国家粮食安全、农民增收、农业增效、农村发展起着重要作用.为此,分析了农机制造在机械工业、东北区域经济中的地位与作用;阐述了农机制造业存在的问题;鉴于目前东北地区农机制造业的现状,提出了其今后发展的措施.  相似文献   

东北地区农机化发展的措施与建议     

于斌  具本弘  魏兆凯 《农机化研究》2007,(10):247-248

农业机械化是农业现代化的基础和手段,没有农业机械化,就没有农业现代化.为此,针对东北地区农业机械化发展的现状和存在的主要问题,提出了东北地区农业机械化发展的措施与建议,旨在为农业现代化建设和新农村建设提供参考.  相似文献   

东北半干旱黑土区玉米秸秆还田方式对土壤水溶性有机碳含量及其组分的影响     

高盼  申慧波  王宇先  蔡姗姗  徐莹莹  杨慧莹  王晨  张巩亮 《干旱地区农业研究》2024,(3):127-135

为明确不同秸秆还田方式下土壤有机碳组分的变化特征,基于6 a秸秆还田长期定位试验,利用三维荧光光谱技术,对无秸秆还田（CK）、秸秆覆盖还田（FG）、秸秆翻埋还田（FM）处理下土壤有机碳（SOC）含量及水溶性有机碳（WSOC）含量及其结构特征进行分析。结果表明：（1）与CK相比,FM处理0~40 cm土层SOC含量提高7.87%~29.54%,FG处理0~30 cm土层SOC含量增加1.91%~18.61%,30~40 cm土层SOC含量降低7.67%;FM和FG处理0~40 cm土层土壤WSOC含量分别提升13.42%~39.42%和0.28%~26.34%。（2）通过WSOC三维荧光光谱发现,各土层CK（Ex/Em=300/34、Ex/Em=300/340、Ex/Em=240/340、Ex/Em=300/340）处理WSOC荧光特征峰为溶解性微生物代谢产物和类色氨酸蛋白质物质荧光峰;FM（Ex/Em=340/430、Ex/Em=340/430、Ex/Em=340/435、Ex/Em=340/435）和FG（Ex/Em=270/440、Ex/Em=270/435、Ex/Em=340/435、Ex/Em=340/430）处理为类腐殖酸类物质荧光特征峰,腐殖化程度较高,结构较为复杂;荧光区域积分表明,FM和FG处理类腐殖酸类物质（Ⅴ）和富里酸类物质（Ⅲ）的积分百分比分别较CK增加12.18%~27.39%、11.98%~30.72%和3.96%~5.73%、2.99%~5.40%。（3）土壤WSOC包含两个组分,C1（Ex/Em=340/435, 270/435）组分为类腐殖酸类物质,C2（Ex/Em=290/345, 240/345）组分为溶解性微生物代谢产物和类色氨酸蛋白质物质;F_max值结果表明,0~40 cm土层的C1组分相对含量表现为FM>FG>CK,表明秸秆翻埋还田更有助于土壤中营养物质含量增加和形成更高分子量的有机物。综上,不同秸秆还田方式均可提升SOC和土壤WSOC含量,增加腐殖化程度,加强土壤的供肥能力,翻埋还田处理提升作用更为显著。  相似文献   

Landscape and Land‐Use Effects on the Spatial Variation of Soil Chemical Properties     

《Communications in Soil Science and Plant Analysis》2012,43(15-16):2389-2412

The current study addressed the spatial variation of soil organic matter (SOM), total nitrogen (TN), extractable phosphorus (EP), and extractable potassium (EK) in agricultural soils of a representative region, northeast China. Soil cation exchange capacity (CEC) and the effects of landscape attributes and land use were also investigated. The techniques used included conventional statistics, geostatistics, and geographic information systems (GIS). Our study demonstrated that EP had the greatest coefficient of variation (CV), and CEC had the least CV. The experimental semivariograms of the five soil chemical properties included in this study were all fitted with exponential models. The five soil variables all showed moderate spatial dependence. The SOM, EK, and CEC decreased with increasing altitude. Significant negative relationships were found between the slope gradient and EP, EK, and CEC. Relatively steeper slopes might result in greater soil erosion, which leads to a decline in soil nutrients. Soil types had significant impacts on all soil chemical properties, which reflect the effect of the parent soil material. In general, the mean values of soil variables for vegetable land were statistically greater than those for upland and paddy fields. After being divided into two parts along the Yinma River, soil samples of the western part have statistically greater SOM, EP, EK, and CEC values than those collected from the eastern part.  相似文献   

横垄耕作的面源污染截留效应研究     

杨育红  阎百兴  严登华 《中国水土保持》2012,(9):46-47

为了解横垄耕作的面源污染截留效应,选取吉林省长春市莫家沟小流域横垄耕作坡耕地为研究区,应用210Pbex核素示踪技术得到研究区土壤侵蚀模数为2 268 t/(km2.a),吸附态氮、磷流失负荷分别为4 889、2 022 kg/a;运用RU-SLE2.0模型,模拟在同等立地条件下顺坡耕作土壤侵蚀模数约为6 200 t/(km2.a)。对比结果表明:横垄耕作较顺坡耕作可减少约63%的土壤流失量及随土壤流失的吸附态氮磷负荷。  相似文献