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The presence of cattle in the Amazon region is controversial in terms of their ecological suitability and profitability compared with crops. Nevertheless, they are widely distributed in the study area in north-eastern Pará and, contrary to the common image of cattle on large ranches, a high proportion of them are kept on smallholder farms. To explain their presence, cattle are assumed to have benefits beyond physical production, such as complementing resource use or representing capital. To test this hypothesis, the costs and benefits of the three main agricultural activities, cattle, cassava and black pepper production, in terms of land, labour and capital productivity, were recorded in 37 small farms over a period of 15 months. To provide a longer perspective, benefits and costs of these activities were calculated for their assumed lifetime, which in the case of cattle, assumed a stable herd, derived from a deterministic herd model. The resultant values for land, labour and capital productivity of cattle were much lower than the values derived from direct observations during the study period, and were not as high as those for cassava and black pepper. Furthermore, the analysis of resource use in the farms showed that cattle production was not usually integrated with cropping activities, did not improve the use of available labour, and competed for land. Therefore, there had to be a reason for keeping cattle beyond their physical productivity. It was deduced to be their functional quality. Cattle could be disposed of quickly and easily at any time, in order to acquire large sums of cash or the equivalent in kind. The liquidity derived from keeping living stock was not matched by other agricultural activities or by the financial market. Hence, cattle turned out to be the best instrument of finance for the smallholder. Farmers were not interested in the continuous development of their herds, or sustainable production practices, and favoured low input management. Consequently, development plans relying on long-term, continuous commitments to pasture and cattle management are inappropriate. Instead, research and extension work should focus on simple, flexible and low-cost improvements to cattle keeping on crop-livestock smallholder farms, until credit programmes are available that replace the financing function of cattle. 相似文献
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《Agricultural Systems》1986,19(2):111-125
The profitability of establishing commercial poultry enterprises supplying the main urban markets in Zaire was evaluated in this study. In 1982 data were collected from eight layer farms, ranging in size from 80 to 150 000 layers per production period, located in Bas-Zaire and areas surrounding Kinshasa, Zaire. In addition, data were also collected from three farms that produced broilers as well as eggs. These poultry enterprises were analyzed, based upon their current level of production capacity, input costs and annual net returns.The results indicate that the profitability of layer farms appeared to be influenced by the rate of mortality, the rate of laying and the high cost of imported supplies such as hatching eggs, baby chicks, medications, vitamins, minerals and protein feeds. A low-cost poultry feed ration that met the requirements for both broilers and layers was developed using mainly Zairian ingredients. Access to lower cost medical supplies, better management practices and cheaper feeds appeared to be the key to expanding commercial poultry enterprises in Zaire and other developing countries. 相似文献
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目前,我国普遍采用的木薯收获方式为人工收获,劳动生产率低、工作环境差且经济效益低下,而国外的木薯收获机普遍不适应于我国南方的粘性土壤,存在木薯损失率高且土壤分离不彻底的问题。查阅资料得知,挖拔式木薯收获机十分适应我国南方的木薯种植环境,可减少木薯损失,促进木薯与土壤的分离。为此,利用UG设计了一款挖拔式木薯收获机,利用Adams软件对机器进行仿真分析得出多组数据,并使用MatLab对这些数据进行处理,以根据运动关系确定关键零件参数,使其可以与目前市面上的拖拉机匹配,实现高效低能耗收获木薯的目的。 相似文献
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《Journal of Agricultural Engineering Research》1987,36(2):97-100
A technique using steam for gelatinizing fermented cassava mash was investigated. The mash which was dewatered to about 50% moisture content (wet basis) was heated to between 88°C and 94°C by steaming. The steamed product when dried had characteristics which compared favourably with five samples of gari produced by conventional techniques. The technique could provide the basis for an alternative technology for gelatinizing fermented cassava mash for gari production. 相似文献
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木薯生产机械化程度低是制约我国木薯产业发展的瓶颈之一,研究高性能的木薯精播机对于促进木薯产业稳定发展具有重要推动作用。木薯精播机结构组成复杂,为提高工作性能,机架必须具有良好的结构与力学性能。本文以课题组研制的双行木薯播种机均匀精量自动排种装置的机架为研究对象,采用UG联合ANSYS软件建立机架的有限元模型,使用ANSYS Work Bench对机架进行静力学分析、约束模态分析以及灵敏度分析。通过模态分析确定优化响应,灵敏度分析确定设计变量,模型建立确定优化目标,多目标优化设计数学模型计算得到6组非劣解。在所得6组方案和初始方案中,基于熵权的模糊物元模型抉择出最优的机架结构方案。双行木薯播种机均匀精量自动排种装置机架优化前后对比分析表明,第一阶模态频率提升3.60%,机架质量减轻8.76%,最大变形减小5.08%,较好的达到了机架轻量化结构优化目的,研究结果可为木薯精播机的设计提供参考。 相似文献
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现阶段,智能化加工装备与技术代表着生产力,是提高生产效率、转变发展方式的物质基础,智能化装备技术在畜禽加工过程中的应用在保证稳定、可靠的生产过程的同时,有着显著的经济效益。总结了智能化装备在畜禽屠宰、分割和分级等加工过程中的应用,归纳了国内外学者在机器视觉、光谱检测、多种技术融合、X射线CT成像和超声波成像等智能化技术在畜禽加工领域的诸多研究成果,分析了当前畜禽加工中存在的智能装备不系统、智能化技术不成熟的问题现状,展望了未来智能装备技术在畜禽加工中设备类型标准、多样化,提高设备集成化水平,促进技术融合等发展趋势,为畜禽加工智能化装备技术研究与行业智能化发展提供相关信息和参考。 相似文献
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Systems analysis techniques were used to compare two selected maize stover systems with a conventional maize silage system for growing beef cattle. All systems were based on a 200 ha integrated farm currently utilizing 160 ha for a cash crop grain maize enterprise and 40 ha of maize silage for a cattle growing operation. The conventional maize silage system fed 423 cattle for an average gain of 160 kg liveweight per animal. Alternative systems fed an equal number of cattle and produced an equal gain per animal. One alternative (ammoniated system) involved harvesting wet maize stover with a forage harvester immediately after grain maize harvest and subsequent treatment with ammonia (4% dry matter basis) at storage. A second alternative (separated system) was designed to harvest and store mature whole-plant maize silage (50–55% H2O) followed by separation into grain and stover fractions at feeding time. Cost per steer for the growing period was calculated using a cost simulation model for each system. The separated system had a lower mean cost per steer, while the ammoniated system had a slightly higher cost per steer than the conventional maize silage system, Can. $189, Can. $197 and Can. $195, respectively. Break-even shelled maize prices, representing the shelled maize price at which each alternative system had an equivalent cost per steer to the conventional system, were calculated. Break-even shelled maize prices were Can. $122 and Can. $140 t?1 for the separated stover and ammoniated stover systems, respectively. The estimated reduction in cost per steer would appear to make the separated stover system feasible even at moderate shelled maize prices. 相似文献
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《Agricultural Water Management》1988,15(2):141-153
The assessment of flood damage costs on farm land is a necessary part of the evaluation of land drainage improvement schemes and maintenance programmes. This paper describes a method to calculate the average annual cost of flooding and the extra benefits or costs associated with given changes in flooding regime. Particular reference is made to the effect of land use, flood frequency and seasonality on flood costs. The method is illustrated by means of a simplified case study which examines the agricultural benefits of reduced summer flooding in an area of environmental importance. 相似文献
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John L. Dillon 《Agricultural Systems》1976,1(1):5-22
There are three broad aspects of Systems Research worthy of particular consideration by professional personnel earning their keep within or about the agricultural research system. I will discuss these three aspects seriatim. The first is the conjecture that the systems approach constitutes a technological change in our mode of thinking about the world of such magnitude as to imply that we are now moving from one sociotechnical age to another. The second aspect, a corollary of the first, is the use of the systems approach as a framework for the selection of research programmes. The third, which also follows from the first, is the efficiency of conducting research on a systems basis. Many would think of this last aspect of efficiency as constituting ‘the economics of systems research’, but I believe the systems approach, via the first two aspects I have mentioned, has far wider implications of economic import for agricultural research. 相似文献
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Most published research concerning the environmental impacts of broiler poultry production is limited to assessments of on-farm gaseous and nutrient emissions. Here, ISO-compliant Life Cycle Assessment was used to predict the broader, macroscale environmental impacts of the material and energy inputs and emissions along the US broiler supply chain. It was found that feed provision accounts for 80% of supply chain energy use, 82% of greenhouse gas emissions, 98% of ozone depleting emissions, 96% of acidifying emissions and 97% of eutrophying emissions associated with the cradle-to-farm gate production of broiler poultry. On-farm inputs and emissions, largely related to heating and ventilation contribute on average only 9% of these impacts. These results underscore the fallacy of “landless farming” and the importance of full supply-chain environmental management for improving sustainability in the US poultry industry. 相似文献
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