Heritability estimates and response to selection for growth of Nile tilapia (Oreochromis niloticus) in low-input earthen ponds

This study presents results of two generations of selection (G₁ and G₂) for growth of Nile tilapia. The selection environment consisted of earthen ponds which were fertilized daily with 50 kg dry matter (dm)/ha chicken manure. No supplementary feeds were provided. In total, 6429 fully pedigreed experimental fish were included in the analysis. Survival till harvest was highly variable ranging from 35% to 77% and was affected by initial weight, pond, and age effects. Body weight at harvest (BW) increased from a mean of 67.4 g in the grandparental (unselected) population (G₀) to 129.5 g in G₂ was affected by initial weight, pond, sex and age effects. Generations were discrete and therefore genetic parameters were estimated separately for each year. Heritability estimates for BW ranged from 0.38 to 0.60, and the heritability for survival ranged from 0.03 to 0.14. The estimated selection response was 23.4 g (34.7%) between G₀ and G₁ and 13.0 g (14.9%) between G₁ and G₂. These results demonstrate the feasibility of selection for growth of Nile tilapia in low-input environments.     

卤虫虾片对水体pH值的影响

通过喂养中国对虾幼体试验，分别以卤虫虾片试验组和传统饵对照组进行。试验表明，在幼体成活率方面，前者稍优于后者，在养殖水体的最主要指标PH方面，二者差别不大。说明投喂卤虫虾片对中国对虾幼体的成活率和水质无良影响，用低值的卤虫虾片代替部分或全部高价的活体饵料是切实可行的，能够满足育苗需要。     

河湖水生态系统服务价值核算研究及应用展望

科学有效地界定河湖水生态系统服务价值评估体系与评估指标,可以促进河湖水生态的可持续发展、合理制定水资源价格、为河湖水生态系统服务价值评估提供参考,同时也为河湖水资源纳入国民经济核算体系提供借鉴,为绿色经济核算提供有力的依据。从河湖水生态系统服务功能、评估体系和评估方法等方面总结了国内外研究进展,分析了现有河湖水生态系统服务体系和评估方法的优缺点。对河湖水生态系统服务评估体系进行了优化,优化后的评估体系包括供给服务、调节服务、文化服务和支持服务4大类以及水资源供给、水质净化、科研教育和固碳能力等19项指标,优化了水资源供给、提供水产品、水质净化、防洪减灾、休闲娱乐、生物多样性保护等6个指标的评估方法。对河湖水生态系统服务价值核算在生态文明建设考核、生态产品价值实现机制、自然资源资产审计以及新时期河湖长制考核实施方面的应用进行了展望。下一步要制订GEP核算技术标准,建设市场化、多元化的生态产品交易体系,将水资源开发、利用及保护情况、水资源管理生态环境效益等指标纳入审计范围,建立以水生态系统为整体、以维护河湖生态系统健康为总目标、以定量评判和可操作性为抓手的新的河湖长制考核体系。     

海洋底部鱼类加工行业价值链提升与优化——基于山东省鱼类企业的调研

中国是水产品加工大国,近年来水产品加工业的发展受到国际环境及国内因素制约,比较优势逐渐下降。本文基于底部鱼类加工企业的实地调查数据,采用价值链分析方法,估算我国水产加工环节中的价值增量,分析加工业中存在的问题及其制约因素,进一步提出相应的改进措施,以提升我国底部鱼类加工业的竞争优势。     

Effect of dietary oxidized oil and vitamin E on growth performance,lipid peroxidation and fatty acid profile of Labeo rohita fingerlings

A 3 × 3 factorial experiment was conducted on Labeo rohita fingerlings to evaluate the effect of dietary oxidized oil and vitamin E. Nine experimental diets were made, based on three degrees of oil oxidation (fresh oil, low oil oxidation and high oil oxidation), and each level of oxidation was further supplemented with three levels of vitamin E (0, 100 and 1,000 mg/kg). Weight gain% and specific growth rate (SGR) of fish fed fresh fish oil and low oil oxidation level were significantly higher than highly oxidized oil. Moreover, vitamin E supplemented fish also showed better growth performance. Oil oxidation caused a significant reduction in the concentrations of α‐tocopherol and increase in TBARS level and antioxidant enzyme activities in fish liver and muscles. However, increasing the dietary vitamin E abrogated these effects. Dietary vitamin E supplementation improved the fatty acid, more specifically polyunsaturated fatty acids profile of oxidized oil fed fish. In conclusion, dietary oxidized fish oil increased the oxidative stress condition of fish but supplementation of high dose of vitamin E prevented lipid oxidation, improved growth performance and fatty acid profile of L. rohita.     

池塘和稻田养殖模式下克氏原螯虾肌肉和肝脏营养成分比较

通过对池塘和稻田2种养殖模式下克氏原螯虾(Procambarus clarkii)的肌肉常规营养成分进行测定,同时,对肌肉和肝胰腺的氨基酸和脂肪酸组成进行测定,从而对其营养品质进行分析评价.结果显示,2种养殖模式下克氏原螯虾粗蛋白和粗脂肪无显著性差异(P＞0.05),池塘养殖模式下水分显著高于稻田模式(P＜0.05),...     

GABA、牛磺酸和pH值影响蝌蚪耐缺氧能力的研究

在水中溶解氧一定的条件下, 将蝌蚪放入50 mL密闭三角瓶内, 观察不同质量分数的牛磺酸、GABA 以及水体不同pH 值对蝌蚪耐缺氧能力的影响。结果显示, 质量分数为0. 4% 的GABA水溶液对蝌蚪耐缺氧能力有极显著改善(P < 0. 01) , 0. 3%的GABA 对蝌蚪耐缺氧能力有显著改善(P < 0. 05)。0. 3%的牛磺酸对蝌蚪耐缺氧能力有极显著改善(P < 0. 01) , 0. 1%、0. 2%、0. 4%、0. 5%的牛磺酸对蝌蚪耐缺氧能力有显著改善(P < 0. 05)。实验证明, GABA、牛磺酸均可提高蝌蚪的耐缺氧能力。而0. 2%的B- 丙氨酸可明显减弱牛磺酸的耐缺氧能力。pH值为5. 4、8. 0时可极显著减弱蝌蚪的耐缺氧能力(P < 0. 01), pH 值为712、7. 7时可显著减弱蝌蚪的耐缺氧能力(P < 0. 05) 。     

Determining reference values for stem water potential and maximum daily trunk shrinkage in young apple trees based on plant responses to water deficit

The use of plant water status indicators such as midday stem water potential (Ψ_stem) and maximum daily trunk shrinkage (MDS) in irrigation scheduling requires the definition of a reference or threshold value, beyond which irrigation is necessary. These reference values are generally obtained by comparing the seasonal variation of plant water status with the environmental conditions under non-limiting soil water availability. In the present study an alternative approach is presented based on the plant’s response to water deficit. A drought experiment was carried out on two apple cultivars (Malus domestica Borkh. ‘Mutsu’ and ‘Cox Orange’) in which both indicators (Ψ_stem and MDS) were related to several plant physiological responses. Sap flow rates, maximum net photosynthesis rates and daily radial stem growth (DRSG) (derived from continuous stem diameter variation measurements) were considered in the assessment of the approach. Depending on the chosen plant response in relationship with Ψ_stem or MDS, the obtained reference values varied between −1.04 and −1.46 MPa for Ψ_stem and between 0.17 and 0.28 mm for MDS. In both cultivars, the approach based on maximum photosynthesis rates resulted in less negative Ψ_stem values and smaller MDS values, compared to the approaches with sap flow and daily radial stem growth. In the well-irrigated apple trees, day-to-day variations in midday Ψ_stem and MDS were related to the evaporative demand. These variations were more substantial for MDS than for midday Ψ_stem.     

风水光互补发电系统多目标优化设计

为了贯彻国家大力发展小水电的政策,满足偏远地区的农村用电需求,可以利用当地的新能源建立风水光互补发电系统,就地发电.为此,在充分考虑互补系统环境价值的基础上,采用了多目标优化策略的模式和模糊线形加权的算法,以确定户用风水光发电系统优化设计的方法,建立互补系统设计的数学模型,并对某村的具体情况进行计算,得出符合实际情况的最优配置.     

论服饰广告的审美创作

服饰广告的本体功能是促进服饰商品的销售。设计师借助美学手段进行审美创作,能巧妙地融服饰广告的经济价值于审美价值之中,从而达到吸引受众眼球,提升服饰商品的知名度、美誉度,实现销售商品的终极目的。从美学的角度对服饰广告创意的表现手法进行审视,有助于指导具体的广告创作实践,提升服饰广告的审美价值,实现美学与服饰广告的完美结合。