Effects of dietary nano and macro iron oxide (Fe2O3) on the growth,biochemical, and hematological profiles of African catfish (Clarias gariepinus) fingerlings

Effects of nano and macro iron oxide as dietary iron sources on the growth, hematological, and biochemical characteristics of African catfish, Clarias gariepinus, fingerlings have been studied. Conventional basal feed was supplemented with nFe₂O₃ and Fe₂O₃ as treatments T₁ and T₂ (each at 0.0, 0.2, 0.4, 0.8, 1.2, and 1.6 g/kg supplementation levels) and given to C. gariepinus fingerlings (initial average weight and length 5.01 ± 0.80 g and 7.0 ± 0.53 cm respectively) for 7 weeks. After 7 weeks, the highest percent weight gains of 395.6% for T₁ and 767.4% for T₂ occurred simultaneously at the supplementation level of 0.4 g Fe kg^?1 dry feed of both treatments, while the highest value for the control was 332.5%. Iron accumulations in liver were 2.727, 1.443, and 1.225 ppm, and red blood cell counts were 2.3, 6.0, and 7.0 x 10¹²/l for the same treatments. Supplementation of iron oxide in both nano and macro forms significantly improved the growth and health indices of C. gariepinus up to a concentration of 0.4 g Fe kg^?1 dry feed. Also macro iron oxide was more effective than the nano form in enhancing fish growth within the supplementation levels (0.2?1.6 g kg^?1) considered.     

Inelastic Seismic Response of Reinforced Concrete Frame Structures Reinforced with HRB500 Steel Bars

To achieve sustainable development of construction industry, the application of HRB500 reinforcement with high strength and high ductility in RC structures is being promoted in civil and structural engineering in China. But few studies focus on seismic behaviors of RC structures reinforced with HRB500 bars. In this analysis, three RC frame structures on the Zone of Fortification Intensity 8 (0.3g) in China reinforced with HRB500, HRB400 and HRB335 bars respectively, are designed confirming to the latest draft of the revising Code for the Design of Concrete Structures. Then inelastic seismic response analyses of the three frames with multiple inputs of ground motions are conducted. The seismic response rules and seismic performances of the RC frame reinforced with HRB500 bars are compared with those frames reinforced with HRB400 and HRB335 bars. The analytical results indicate that under ground motions in rare earthquake level, the maximum displacements of the frame reinforced with HRB500 bars are roughly the same as those of the frames reinforced with HRB400 and HRB335 bars, while the rotation ductility demand of elements in the former structure is smaller than those of elements in the latter structures. It is also found that the frame reinforced with HRB500 bars develops a plastic energy dissipation mechanism that is dominated by beam hinges under major earthquake, and the maximum inter storey drift of the frame can satisfy the requirement in the Code for the RC Frame Structures.     

Processing Method Effect on Texture,Color, and Microbial Load of Channel Catfish Fillets

Abstract

Catfish shelf life depends largely on post-harvest handling and storage conditions. Three methods of processing catfish fillets were studied to evaluate quality and shelf life. In one method catfish were hand-dressed, chilled in water at 0°C, and hand-filleted (HC). In the other methods, catfish were mechanically filleted and chilled immediately (MC) or held unchilled for one hour at 18°C prior to chilling (MU). All fillets were stored in HDPE bags at 2°C for analyses at 0, 3, 6, and 9 d. Shear force for MC and MU fillets decreased (P ≤ 0.05) to the same levels as HC fillets after 3 d storage. HC fillets had higher (P ≤ 0.05) ‘L’ and ‘b’ and lower ‘a’ values than MU or MC fillets throughout storage. Initial psychrotrophic counts (PPC) were lower (P ≤ 0.05) for MC (3.9 log CFU/g) and MU (4.1 log CFU/g) than for HC fillets (5.2 log CFU/g). The PPC increased (P ≤ 0.05) after 3 and 6 d in HC and MU fillets, respectively. Coliform growth showed similar patterns as PPC. Spoilage levels indicated a doubling in shelf life of machine-cut fillets (～8 d) as compared to hand-cut fillets (～4 d).     

The evolution of farm management,production efficiencies,and current challenges to catfish production in the United States

Abstract

The catfish industry is the most successful aquaculture business in the US. The development and growth of the catfish industry has resulted in complex fish farm businesses that require intensive management. Technological innovations have resulted in increased yields (land use efficiency). However, in more recent years, productivity gains have not kept pace with the rate of increase in input costs. Increasing intensification of catfish production over time has been accompanied by increased use of debt capital that results in higher levels of financial risk. While still a profitable activity, real profit margins have declined as financial risk has increased. New technologies will likely continue to increase productivity over time. Market‐oriented agribusiness approaches to catfish marketing are likely to become the norm. The challenge for the catfish industry is to coordinate adoption of new higher‐cost technologies with demand increasing market development to sustain farm price levels.     

猪圆环病毒2型基因组DNA的结构与功能研究进展

猪圆环病毒2型(PCV2)是引起猪圆环病毒病相关疾病的主要致病原,可损伤宿主的免疫系统,加剧一些细菌病和病毒病感染的临床症状,在全球养猪业中造成巨大损失。PCV2的基因组DNA含有11个开放阅读框(ORFs),其中至少有7个ORFs编码的蛋白质分子质量大于5ku,但目前只有5种编码的蛋白(Rep、Rep'、Cap、ORF3和ORF4)发现于PCV2复制过程中。作者概述了当前PCV2基因组DNA的结构与功能,阐明PCV2的病原学,为防控PCV2感染提供科学依据。     

3种淡水鱼血浆中游离磷脂的有效性测定

[目的]检测鲤鱼、鲫鱼和鲶鱼3种淡水鱼血浆中游离磷脂的有无,为探索3种淡水鱼凝血现象的生理机制奠定基础。[方法]采用加热兔脑磷脂凝血有效性试验检测加热磷脂的活性,将80℃水浴加热20min后的兔脑磷脂分别加入兔的少血小板血浆、鲤鱼、鲫鱼和鲶鱼的无细胞血浆,测定各血浆加热磷脂的活化部分凝血酶原时间（APTT）。[结果]各试验动物血浆加热磷脂的APTT平均值与对照间差异不显著（P〉0.05）,说明其凝血功能未发生变化;鲤鱼、鲫鱼和鲶鱼的CFP和家兔的不同稀释倍数的PPP的混合血浆平均凝固时间与对照间存在极显著差异（P〈0.01）。[结论]鲤鱼、鲫鱼和鲶鱼的CFP中不含游离的磷脂,它们CFP在无磷脂存在的条件下也可以发生凝固。     

斑点叉尾鮰的人工繁殖技术

阐述了斑点叉尾的人工繁殖技术，其中包括亲鱼池的条件、亲鱼的选择与培育、亲鱼的产卵以及鱼卵的孵化。