The effect of forage quality on predicted enteric methane production from dairy cows

The current study is aimed at determining the effect of different grass silages on enteric methane production from dairy cows and to determine the effect of changing the forage/concentrate ratio on enteric methane production. In the current study, enteric methane was not measured from animals, rather it was estimated using existing equations from the literature. Rations were formulated using six grass forages as the core for the rations. An existing model (SAC FeedByte), which simulates the physical processes based on least cost diet formulation and linear programming modelling, was used to formulate the rations. Enteric methane (/cow/day) that would be produced had a cow been fed that ration was calculated using a set of two different equations. The proportion of concentrates relative to the silage had a significant (p < 0.001) effect on enteric methane production. The results showed that high-quality silage resulted in low enteric methane emissions/litre of milk. Also, a high proportion of concentrate in the ration resulted in low amount of enteric methane produced/kg of milk. Carbon footprinting of dairy production systems should, therefore, account for the variation in forage quality.     

基于供应链视角的海产品物流质量管理研究

海产品物流质量的管理贯穿于从"渔船到餐桌"的整个供应。论文以供应链管理为指导,在物流质量管理基本原理的基础上,界定了海产品物流质量管理的内涵,构建了海产品供应链物流质量管理的模式,提出通过供应链外部质量监管体系和市场准入机制加强海产品供应链外部物流质量控制,通过HACCP质量管理体系实现海产品供应链物流质量的自我约束和内部控制。     

Effect of conserving habitat for biodiversity on optimal management of non-industrial private forests in Florida

Healthy forests and enhanced habitat for wildlife is a growing concern among public and policy makers. These concerns have led to substantial interest in promoting various regulatory and voluntary compliance policies to further biodiversity on private forests. These policies, however, might result in additional cost to forestland owners. In this paper, we estimate the opportunity cost of adopting various biodiversity-friendly forest practices. We do this in the context of slash pine, a dominant commercial tree plantation species in Florida. Results suggest that prescribed burning, invasive species control, maintaining streamside buffer zones, and extending timber harvest beyond the optimal rotation age would significantly decrease the profitability of slash pine forestry. If the major objective of landowners is to maximize profits, results indicate that they are less likely to adopt these practices at socially desirable levels without a policy support. More specifically, results suggest that an annual payment of $38–83 per hectare is required for landowners to adopt these practices. The paper further argues that application of mere command-and-control approaches to implement these practices may result in conversion of private forests to other competitive land uses.     

Multiple objectives and perceptions of optimal management: The Danish industrial fishery in the North Sea

Fisheries management involves many stakeholders with differentopinions about how the fishery should be optimally managed.This paper presents a multi-objective bio-economic model, whichis able to incorporate the preferences of managers and otherstakeholders. The model is a weighted goal programme coveringthe Danish industrial fishery. Economic, political and biologicalconcerns are considered simultaneously and, by applying thepreference structures of different stakeholders, it shows howthe optimally managed fishery would look from the perspectiveof managers and various interest groups. Managers, in this casethe Danish Ministry of Food, Agriculture and Fisheries, areprovided with a management tool that shows the consequencesof their preferences towards the objectives, and can be comparedwith optimal solutions as perceived by other stakeholders.     

The multiple effects of carbon values on optimal rotation

Non-consumptive benefits which increase with crop age, like keeping carbon sequestered, lengthen optimal rotation compared with rotation for timber alone. High proposed carbon prices may extend rotation indefinitely. Carbon storage in wood products reduces this tendency. Biomass as an energy source displacing fossil fuels favours rotations near those of maximum biomass productivity. Use of sawn timber to displace structural materials with high embodied carbon favours somewhat longer rotations. Effects of rotation on soil carbon, and fossil carbon volatilised in harvesting operations, are further complications. Including all carbon effects results in optimal rotations somewhat longer than those based only on timber value, but shorter than those based on timber plus forest carbon. To include all factors intuitively is not possible: balanced appraisal needs economic calculations.     

农产品冷链物流质量安全管理研究

冷链物流的有效管理已成为差异化经营、保障食品安全和赢得市场竞争的现实需要,其发展对于保障农产品质量安全意义重大。文章分析了农产品冷链物流质量安全管理的概念及问题,从经济和社会两方面探讨加强农产品冷链物流质量安全管理的重要性,通过对我国农产品冷链物流的SWOT定性分析,从冷链流程和商业运行模式两方面提出加强农产品冷链物流质量安全管理的方法和措施,最后给予展望与总结。     

关于浙江平阳加强木质渔船质量管理的几点建议

目前小型木质渔船在海洋捕捞中仍占一定的比例,其管理难度较大;本文在调查研究的基础上总结经验、分析现状,针对存在的问题,提出具体的对策措施充分认识必要性,不断增强责任感;强化监管抓源头,重在服务保质量;务实求真创新路、再接再厉上台阶.     

加强镇江市水产品质量安全管理的思考

水产品质量安全问题已成为全社会关注的热点和焦点。近年来,镇江市加快了水产品质量安全建设步伐,并取得了初步成效,也积累了一定的经验。本文从水产生产特点出发,分析了影响水产品质量安全的主要因素,并针对现状,从构建水产品质量安全管理体系、明确水产品质量安全管理重点和规范水产品质量安全管理行为等三方面,提出了加强镇江市水产品质量安全建设和管理的应对措施。     

优化渔政管理资源探析——浙江永嘉县楠溪江渔政管理在“包江”以后的思考

浙江永嘉县楠溪江自"包江"以后就深陷"公地悲剧",存在着形成集体保护的多种制约因素。"分段承包,群管与专管结合的管理模式"是破解迷局,形成集体保护的最佳选择。要完善群管与专管结合的管理模式,吸收各方利益群体服务楠溪江渔业资源保护工作,建立一套促成集体行动的系统机制,构成一个对违法分子强大的心理压力与违法成本压力,收到一种"一旦发现有人毒鱼,邻居会到渔政领赏"的监管效果。     

黑龙江省三江自然保护区的管理问题初探

分析了三江自然保护区在管理中存在的问题：保护管理与周边居民生存权利的冲突;农民使用大量的农药和化肥造成环境污染;保护区管理资金短缺,科研实力薄弱;提出对保护区周边的居民进行教育和经济补偿,解决农民为了生存对保护区资源破坏的问题;引导农民发展有机农业;实行企业化的管理,开发绿色食品;对有经济价值的可再生资源进行开发;开展生态旅游;与高等院校密切合作,引进人才。     

四湖流域综合管理研究

流域内各种自然资源和不同区域之间存在着密切联系,是相互制约和互相关联的统一体。四湖流域存在洪涝灾害、水体污染、生态退化和血吸虫病等生态环境问题,只有通过流域综合管理,采取各种生态措施,加强景观生态建设,才能从根本上消除四湖流域内的各种生态环境问题,促进流域生态的良性循环和社会经济的持续稳定发展。     

Role of information in the adoption of best management practices for water quality improvement

This study investigates the role of information in influencing the adoption of improved farm management practices. A lack of producer information regarding both the profitability and the environmental benefits of adopting improved practices may be a reason why widespread adoption of these practices has not occurred. Compared to direct regulation or financial incentives, raising producer information levels may be a more cost-effective method of increasing adoption. The United States Department of Agriculture has recently established and begun implementing a program based on this idea. To test the validity of the program, a two-stage adoption model is specified and estimated using data from a survey of producers in the program area. The results indicate that producer perceptions Play an important role in the decision to adopt. Changing these perceptions by means of an educational program may be a reasonable alternative to financial incentives in encouraging BMP adoption.     

表面活性剂对牙齿的溶蚀作用

人体牙齿中含有大量的钙离子,而表面活性剂具有溶蚀钙离子的作用.笔者通过EDTA滴定法,在模拟人体口腔温度的条件下,利用不同的表面活性剂溶液浸泡牙齿,研究不同的表面活性剂对牙齿中钙离子的溶蚀程度.从而评价表面活性剂对人体牙齿的长期影响.     

土地储备资金的管理与核算

当前土地储备资金管理与核算中的问题土地储备资金管理主体不规范目前我国土地储备机构体制不统一,使土地储备资金管理主体也不规范。据了解,北京市土地储备中心是政府全额拨款的事业单位,并实行企业化管理运作;南京市土地储备中心明确为事业单位,隶属于市国土局;福州市土地资产发展中心是与市国土资源局平级的事业单位;厦门市的土地储备机构则是“公司”。这些机构的职能基本相同,性质却有很大差异,以至于在土地储备资金管理中,行使的管理权限也大不相同。但就现阶段看,这些土地储备机构无论以何种形式出现,其实质都不是一种严格意义上的市…     

我国渔业科技资源优化配置路径探讨

渔业科技资源的合理配置直接影响着渔业科技资源效用的发挥,渔业科技资源效用不仅体现在其产生的经济效益,还应包括其产生的社会生态效益.本文在分析渔业科技资源配置现状的基础上,从经济学角度阐述了基于可持续发展观的渔业科技资源优化配置的意义,并指出优化配置渔业科技资源的路径选择.     

Effects of resin tapping on optimal rotation age of pine plantation

This paper analyses the effects of resin benefit on the optimal rotation age of Simao pine plantation. Timber growth and resin yield functions were first derived, and then an integrated formulation for Hartman rotation was solved by taking both timber and resin benefits into consideration through numerical optimization. Empirical results indicate that: (1) the inclusion of resin benefit results in lengthening optimal rotation age; (2) resin benefit has a greater effect on rotation age when discount rate is low than when it is high, ceteris paribus; (3) with an improvement of site productivity, resin benefit has a decreasing effect on rotation age, other factors being constant. These effects are also true with respect to benefit gains in present value.     

粮食流通管理条例

中华人民共和国国务院令第407号《粮食流通管理条例》已经2004年5月19日国务院第50次常务会议通过,现予公布,自公布之日起施行。总理二四年五月二十六日