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21.
A conceptual framework is developed and used for improving the livelihood of Sub-Saharan communities faced with multiple stresses resulting from adverse environments, vector-transmitted diseases, and limited food. Ecosocial systems are the units for management. The accumulation of ecological, economic, and social capital is the objective of management, the reduction of maintenance costs is the key strategy, and technologies must satisfy ecological, economic, and social criteria. Interacting social system components are communities, facilitators, scientists, and political as well as administrative organizations. An adaptive approach to management allows flexibility in human and financial resource allocation and results in changes in knowledge and efficacy of management operations. The implementation strategy at two sites in Ethiopia relies on a two-stage procedure. In Stage 1, human and cattle health management set the conditions for development. In Stage 2, the ecosocial system is kept on a trajectory to enhanced ecological, economic, and social capital. In each stage, the assignment of responsibilities leads to four implementation phases. In Stage 1, successful precision targeting of tsetse and drug-based Trypanosoma spp. control increased the economic and social capital at the Luke site in southwestern Ethiopia but threatened the ecological capital because of overstocking and land degradation. In Stage 2, a women’s group living in the outskirts of Addis Ababa (Ethiopia) transformed barren land into a horticultural enterprise to enhance ecosystem service provision, including production of horticultural goods, and increase soil fertility expressed by nutrients and water availability. This article reviews concepts on human livelihood improvement in Sub-Saharan Africa and identifies principles that became important during project execution.  相似文献   
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The introduction of livestock, including the rabbit and the fallow deer, to Britain is reviewed, and a summary is given of the history of husbandry arid selective breeding. The feeding or stock on foliage and its importance for survival through the winter is described. The meaning of domestication is discussed and ii is argued that there should be no separation between the old established breeds of livestock, park deer, and feral populations including Chillingham rattle, Soay sheep, and Bagot goats; all belong to the assemblage of large mammals that has created the landscape of the British Isles.  相似文献   
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In response to environmental threats, numerous indicators have been developed to assess the impact of livestock farming systems on the environment. Some of them, notably those based on management practices have been reported to have low accuracy. This paper reports the results of a study aimed at assessing whether accuracy can be increased at a reasonable cost by mixing individual indicators into models. We focused on proxy indicators representing an alternative to the direct impact measurement on two grassland bird species, the lapwing Vanellus vanellus and the redshank Tringa totanus. Models were developed using stepwise selection procedures or Bayesian model averaging (BMA). Sensitivity, specificity, and probability of correctly ranking fields (area under the curve, AUC) were estimated for each individual indicator or model from observational data measured on 252 grazed plots during 2 years. The cost of implementation of each model was computed as a function of the number and types of input variables. Among all management indicators, 50% had an AUC lower than or equal to 0.50 and thus were not better than a random decision. Independently of the statistical procedure, models combining management indicators were always more accurate than individual indicators for lapwings only. In redshanks, models based either on BMA or some selection procedures were non-informative. Higher accuracy could be reached, for both species, with model mixing management and habitat indicators. However, this increase in accuracy was also associated with an increase in model cost. Models derived by BMA were more expensive and slightly less accurate than those derived with selection procedures. Analysing trade-offs between accuracy and cost of indicators opens promising application perspectives as time consuming and expensive indicators are likely to be of low practical utility.  相似文献   
26.
Reproductive performance has recently been a growing concern in cattle dairy systems, but few research methodologies are available to address it as a complex problem in a livestock farming system. The aim of this paper is to propose a methodology that combines both systemic and analytical approaches in order to better understand and improve reproductive performance in a cattle dairy system. The first phase of our methodology consists in a systemic approach to build the terms of the problem. It results in formalising a set of potential risk factors relevant for the particular system under consideration. The second phase is based on an analytical approach that involves both analysing the shapes of the individual lactation curves and carrying out logistic regression procedures to study the links between reproductive performance and the previously identified potential risk factors. It makes it possible to formulate hypotheses about the biotechnical phenomena underpinning reproductive performance. The last phase is another systemic approach that aims at suggesting new practices to improve the situation. It pays particular attention to the consistency of those suggestions with the farmer's general objectives. This methodology was applied to a French system experiment based on an organic low-input grazing system. It finally suggested to slightly modify the dates of the breeding period so as to improve reproductive performance. The formulated hypotheses leading to this suggestion involved both the breed (Holstein or Montbéliarde cows), the parity, the year and the calving date with regard to the turnout date as the identified risk factors of impaired performance. Possible use of such a methodology in any commercial farm encountering a biotechnical problem is discussed.  相似文献   
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ABSTRACT Depredation of livestock by large carnivores is an important but poorly understood source of human-carnivore conflict. We examined patterns of livestock depredation by jaguars (Panthera onca) and pumas (Puma concolor) on a ranch-wildlife reserve in western Brazil to assess factors contributing to prey mortality. We predicted jaguars would kill a greater proportion of calves than yearling and adult cattle and that proximity to suitable habitat would increase mortality risk. We further speculated that exposure to predation risk would promote livestock grouping and increased movement distance. We recorded 169 cattle mortality incidents during 2003–2004, of which 19% were due to predation by jaguars and pumas. This level of mortality represented 0.2–0.3% of the total livestock holdings on the ranch. Jaguars caused most (69%) cattle predation events, and survival in allotments was lower for calves than for other age classes. Forest proximity was the only variable we found to explain patterns of livestock mortality, with predation risk increasing as distance to forest cover declined. Due to low predation risk, cattle movement patterns and grouping behavior did not vary relative to level of spatial overlap with radiocollared jaguars. The overall effect of predation on cattle was low and livestock likely constituted an alternative prey for large cats in our study area. However, selection of calves over other age cohorts and higher predation risk among cattle in proximity to forest cover is suggestive of selection of substandard individuals. Cattle ranchers in the Pantanal region may reduce cattle mortality rates by concentrating on losses due to nonpredation causes that could be more easily controlled.  相似文献   
28.
Abstract: Problem Animal Control Registers, where farmers report livestock losses due to predators as a prerequisite for financial compensation, allow quantifying the human-predator conflict. We analyzed such registers from the Kweneng District of Botswana to assess the impact of native predators on livestock over 3 years. Leopards (Panthera pardus), lions (Panthera leo), wild dogs (Lycaon pictus), brown hyenas (Hyaena brunnea), and cheetahs (Acinonyx jubatus) altogether claimed 2,272 head of livestock. During 2002, the year with the highest impact, the number of animals reported depredated (954) represented 0.34% of the livestock in the district. Leopards and lions caused 64% of the losses. Leopard livestock predation mainly affected calves and was consistent over the district and over time. In contrast, lion predation concentrated on adult cattle, was characterized by local hot spots close to reserve borders, decreased with increasing distance to a reserve, and increased during 2002, an unusually dry year. Interviews with 60 farmers and herders within 30 km of Khutse and Central Kalahari Game Reserves revealed an annual loss of 2.2% of their livestock to predators. Here, small farms (max. 100 domestic animals) suffered relatively higher losses than large, commercial farms, not only due to predation (small farms: 11.7%; large farms: 1.0%) but also from other causes (small: 12.6%; large: 2.8%), even though herders on large farms guarded 5 times more livestock per person than those on small farms. To reduce livestock predation in most of the district where lions are absent, we recommend maternity corrals for pregnant females and calves to better protect vulnerable calves during day and night. In areas close to a reserve where lions roam, herders' incentives to keep all livestock protected in a corral at night have to be enhanced because, according to the registers, only 3 predation cases were reported to have happened inside a corral.  相似文献   
29.
Reduced genetic variation among hosts may favour the emergence of virulent infectious diseases by enhancing pathogen replication and its associated virulence due to adaptation to a limited set of host genotypes. Here, we test this hypothesis using experimental evolution of a mouse-specific retroviral pathogen, Friend virus (FV) complex. We demonstrate rapid fitness (i.e. viral titre) and virulence increases when FV complex serially infects a series of inbred mice representing the same genotype, but not when infecting a diverse array of inbred mouse strains modelling the diversity in natural host populations. Additionally, a single infection of a different host genotype was sufficient to constrain the emergence of a high fitness/high virulence FV complex phenotype in these experiments. The potent inhibition of viral fitness and virulence was associated with an observed loss of the defective retroviral genome (spleen focus-forming virus), whose presence exacerbates infection and drives disease in susceptible mice. Results from our experiments provide an important first step in understanding how genetic variation among vertebrate hosts influences pathogen evolution and suggests that serial exposure to different genotypes within a single host species may act as a constraint on pathogen adaptation that prohibits the emergence of more virulent infections. From a practical perspective, these results have implications for low-diversity host populations such as endangered species and domestic animals.  相似文献   
30.
Ecosystem services are typically valued for their immediate material or cultural benefits to human wellbeing, supported by regulating and supporting services. Under climate change, with more frequent stresses and novel shocks, 'climate adaptation services', are defined as the benefits to people from increased social ability to respond to change, provided by the capability of ecosystems to moderate and adapt to climate change and variability. They broaden the ecosystem services framework to assist decision makers in planning for an uncertain future with new choices and options. We present a generic framework for operationalising the adaptation services concept. Four steps guide the identification of intrinsic ecological mechanisms that facilitate the maintenance and emergence of ecosystem services during periods of change, and so materialise as adaptation services. We applied this framework for four contrasted Australian ecosystems. Comparative analyses enabled by the operational framework suggest that adaptation services that emerge during trajectories of ecological change are supported by common mechanisms: vegetation structural diversity, the role of keystone species or functional groups, response diversity and landscape connectivity, which underpin the persistence of function and the reassembly of ecological communities under severe climate change and variability. Such understanding should guide ecosystem management towards adaptation planning.  相似文献   
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