Extensive Livestock Production Research Articles

Comparing biodiversity between protected savanna and adjacent non-protected farmland in the southern Kalahari

In this study we investigated the effect of different land use options (wildlife versus livestock) on species richness of plants and reptiles in the protected Kgalagadi Transfrontier Park (KTP) versus adjacent non-protected farmland within the same savanna habitat type (Aoub dune veld) in the southern Kalahari, South Africa. Our results show that both plant and reptile species richness as well as plant cover and reptile abundance was significantly higher in the protected KTP than in the non-protected farmland. The higher proportion of shrub but lower proportions of perennial grass cover, herb cover, and herb species richness in the farmland can be explained by higher stocking rates and the differences in feeding behaviour between native wild ungulates (e.g. Antidorcas marsupialis, Oryx gazella) and livestock (mainly sheep). The reptile’s prey availability and microhabitats (perennial grass tussocks and rodent burrows) for thermoregulation and protection against predators were significantly lower in the farmland. To conclude, our results clearly show that long term effects of different land use options (wildlife in protected KTP versus extensive livestock production in the non-protected farmland) even within the same habitat type have led to significant changes in vegetation composition, availability of microhabitat structures and in the reptile community.

Dealing with drought: social implications of different smallholder survival strategies in semi-arid rangelands of Northern Patagonia, Argentina

Drought is a constant part of rangeland dynamics in arid and semi-arid regions, and has enormous impacts on extensive livestock production by reducing outputs as well as by generating short-term farm decapitalisation (e.g. when livestock die). Since rural people rely on animal husbandry for their livelihood, productive losses become a social problem. Approaches to deal with drought have generally been focused on the livestock–range management linkage, with many suggestions originating from different disciplines. However, fewer efforts had been made to understand the adaptive capacity of households to cope with drought, through changing from on-farm to off-farm approaches. We assessed the implications for household gross income of different smallholder survival strategies, in the context of a severe regional drought. Three strategies were selected: (i) social networks involving partnerships, (ii) income diversification, and (iii) farm production diversification. While drought impacted homogeneously on the production indicators among the different strategies, differences were apparent in household economic performance. Better prices obtained from associated sales and off-farm income strategies registered better household gross income levels. For these cases the effect of drought on farm productivity could be decoupled from household income. Results provide new insights in understanding the social impact of drought on rangelands, challenging current ideas about how governments can support poorest and most vulnerable farmers in rural arid and semi-arid regions.

Enabling technologies to improve area‐wide integrated pest management programmes for the control of screwworms

The economic devastation caused in the past by the New World screwworm fly Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) to the livestock industry in the U.S.A., Mexico and the rest of Central America was staggering. The eradication of this major livestock pest from North and Central America using the sterile insect technique (SIT) as part of an area-wide integrated pest management (AW-IPM) programme was a phenomenal technical and managerial accomplishment with enormous economic implications. The area is maintained screwworm-free by the weekly release of 40 million sterile flies in the Darien Gap in Panama, which prevents migration from screwworm-infested areas in Columbia. However, the species is still a major pest in many areas of the Caribbean and South America and there is considerable interest in extending the eradication programme to these countries. Understanding New World screwworm fly populations in the Caribbean and South America, which represent a continuous threat to the screwworm-free areas of Central America and the U.S.A., is a prerequisite to any future eradication campaigns. The Old World screwworm fly Chrysomya bezziana Villeneuve (Diptera: Calliphoridae) has a very wide distribution ranging from Southern Africa to Papua New Guinea and, although its economic importance is assumed to be less than that of its New World counterpart, it is a serious pest in extensive livestock production and a constant threat to pest-free areas such as Australia. In the 1980s repeated introductions and an expansion of Old World screwworm populations were reported in the Middle East; in the 1990s it invaded Iraq and since late 2007 it has been reported in Yemen, where a severe outbreak of myiasis occurred in 2008. Small-scale field trials have shown the potential of integrating the SIT in the control of this pest and various international organizations are considering using the release of sterile insects as part of an AW-IPM approach on a much wider scale. Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae) is a screwworm of temperate regions, which, although of limited agricultural importance, has invaded several new locations in the past few years. This special issue reports on the results of a 6-year project funded by the Joint Food and Agriculture Organization of the United Nations/International Atomic Energy Agency (FAO/IAEA) Programme of Nuclear Techniques in Food and Agriculture entitled 'Enabling Technologies for the Expansion of the SIT for Old and New World Screwworm'. A major goal of the project was to better understand population genetic variation in screwworms as an aid to the identification of isolated populations. The project also addressed issues related to genetic sexing, cuticular hydrocarbons, population dynamics, genetic transformation and chromosome analysis.

Forage–cattle relationships in a communally managed semi-arid savanna in northern Zululand, South Africa

Development of extensive livestock production in KwaZulu-Natal is constrained by seasonal variability of rangeland production and low forage nutritional quality. A three-year study was implemented to determine the seasonal variation in herbaceous biomass and chemical composition of veld, animal weight, body condition and blood metabolites in a communal area where farmers wished to commercialise. The period of study was not characterised by unusual climatic conditions. Herbaceous biomass increased in wet months and decreased in dry months. Crude protein concentration was higher in wet seasons than dry seasons. Neutral detergent fibre was generally high. Calves gained 0.53–0.63 kg d−1 during the wet season and took 15 months to reach weaning weight. The mean weights and body condition scores of cows and bulls increased during wet seasons and decreased during dry seasons. Blood urea nitrogen was low in the dry season while creatinine concentrations increased in the dry season and dropped in the wet season. The results indicated that the quantity and quality of forage were insufficient for the development of commercial beef production. Further research is needed to develop and test strategies for improving the availability of nutrients in situations where communal farmers wish to develop livestock production.

Beef Production and Greenhouse Gas Emissions

In their article discussing the impacts of farm animal production on climate change, Koneswaran and Nierenberg (2008) called for “immediate and far-reaching changes in current animal agriculture practices” to mitigate greenhouse gas (GHG) emissions. One of their recommendations was to switch to organic livestock production, stating that Raising cattle for beef organically on grass, in contrast to fattening confined cattle on concentrated feed, may emit 40% less GHGs and consume 85% less energy than conventionally produced beef. These claims are terribly misleading. Koneswaran and Nierenberg (2008) compared organic beef produced in Sweden (22.3 kg of carbon dioxide-equivalent GHG emissions per kilogram of beef) with unusual and resource-intensive Kobe beef production in Japan (36.4 kg of CO2-equivalent GHG emissions per kilogram) (Cederberg and Stadig 2003; Ogino et al. 2007). To achieve the ultra-high fat levels in meat preferred by Japanese consumers, Japan’s wagyu cattle are raised and fattened for more than twice as long as typical U.S. beef cattle (Cattle Marketing Information Service Inc. 2007; Ogino et al. 2007). Moreover, all of the feed and forage for the Japanese animals (from birth through slaughter) must be shipped especially long distances—> 18,000 miles in the example cited. Hence, this beef has ultra-high GHG emissions and energy requirements. According to several analyses, typical nonorganic beef production in the United States results in only 22 kg of CO2-equivalent GHG emissions per kilogram of beef, which is 0.3 kg less than the Swedish organic beef system (Johnson et al. 2003; Subak 1999). These comprehensive life cycle analyses, which examined all aspects of beef production and all GHG emissions, seem to definitively rule out significant reductions in GHG emissions by switching to organic beef production. In fact, if nitrous oxide and other emissions from land conversion are included in the analysis, a large-scale shift to organic, grass-based extensive livestock production methods would increase overall GHG emissions by nearly 60% per pound of beef produced. According to Searchinger et al. (2008), each acre of cleared land results in 10,400 lb/acre/year of CO2-equivalent GHG (over a 30-year period, based on estimated emissions from a proportion of each land type converted to cultivation in the 1990s). Our own analysis (Avery and Avery 2007) using conservative beef production parameters from Iowa State University’s Leopold Center for Sustainable Agriculture shows that grain-finishing cattle is at least three times more land efficient per pound of finished beef compared to grass-finishing. Cattle industry statistics [U.S. Department of Agriculture (USDA) 2008] show that, in 2007, the United States used 2 billion bushels of corn to produce 22.16 billion lb finished grain-fed beef (17.3 million head steers and 10.2 million head heifers at average dressed weights of 830.2 and 764.8 lb, respectively). At 150 bushels/acre corn, this means we used 13.3 million acres to produce the feed grains. Converting all beef production to grass-based finishing would require at least an additional 26.6 million acres of pasture/grass to produce 2007 U.S. beef output. Using the 22 lb of CO2-equivalent GHG per pound of grain-fed beef from Johnson et al. (2003) and the 22.3 lb CO2-equivalent GHG per pound of beef for organic grass of Cederberg and Stadig (2003), each system producing 22.16 billion lb of beef would directly and indirectly result in 487.5 and 494.2 billion lb of CO2-equivalent GHG emissions, respectively. However, adding the “carbon debt” resulting from the additional cleared land required by the two-thirds less efficient grass finishing process (26.6 million acres × 10,400 lb/acre/year, or 276.6 billion lb/year) results in the organic system totaling 770 billion lb of CO2-equivalent GHG emissions; or 58% higher than the conventional system’s total of 487.5 billion lb.

Interactions in integrated US agricultural systems: The past, present and future

AbstractDuring the 20th century, American agriculture underwent dramatic changes. At the beginning, farms were more diverse, dependent on animal traction, on-farm inputs and income and, after initial land grants, nearly independent of government policy. However, external issues, such as government policies, mechanization, fossil fuel costs, increased consolidation and vertical integration of markets and increased societal awareness of the environment and concern with farming practices, have substantially altered the structure of agriculture. These external issues are significant drivers of agriculture and we grouped them into social/political, economic, environmental and technological drivers. Previous papers have examined specific effects of these drivers. Our objective is to examine how these drivers interact and influence today's agricultural systems. We developed four categories: (1) Commodity Crop Production, (2) Supply Chain Livestock Production, (3) Organic Production and (4) Extensive Livestock Production, to describe major current agricultural systems. These categories were developed as major and contrasting systems but do not represent all of American agriculture. Although it is not possible to predict the future, interactions among the various drivers will affect these systems differently. By examining multiple scenarios, we conclude the highly specialized systems (Nos. 1 and 2) are highly vulnerable to future changes, and that developing adaptive capacity is critical for dealing with new uncertainty. Sustainable agricultural systems will need balance among various domains to be able to adapt and survive. We suggest that the concept of dynamic-integrated agricultural systems may be the best way to meet this goal because of its ability to consider multiple goals and flexible producer decision-making.

Nitrogen deposition and loss of biological diversity: Agricultural land retirement as a policy response

Current levels of nitrogen deposition, especially ammonia, seriously impact upon ecosystems biological diversity. However, land use policy maintaining and enhancing key ecosystems in the UK in most cases does not explicitly take account of this pollution in terms of onsite management prescriptions. In this paper the economic potential of agricultural land retirement to reduce localised nitrogen deposition is examined. Employing a case study that combines nitrogen deposition modelling and agricultural land use change, reductions in nitrogen deposition necessary to reverse the loss of floral diversity are examined. The results indicate that agricultural land retirement is in principle a potentially useful policy instrument for dealing with nitrogen deposition from extensive livestock production.

Sugarcane ethanol production in Brazil: an expansion model sensitive to socioeconomic and environmental concerns

AbstractBrazilian agriculture is characteristically dynamic; land and production resources have a skewed ownership distribution; and agricultural production is essential for small holders of rural poor regions. Also, the main agricultural land use is composed of pastures where extensive livestock production prevails. Because of increasing demand Brazil is expected to expand its sugarcane‐based ethanol production. Addressing concerns about social and environmental impacts of such an expansion requires careful consideration of the complexity of Brazilian agriculture in general and specific local conditions in particular. This perspective outlines an expansion model for sugarcane ethanol production that is sensitive to socioeconomic and environmental concerns. Through integration with the prevailing land use, the model avoids the usual displacement of extensive livestock production to remote regions, causing leakage effects with deforestation and promotes milk and beef cattle intensification and investment opportunities for local society. The expansion model is feasible at current market conditions and should have good prospects for complying with sustainability criteria within various certification schemes presently under development. A case study, developed in the Pontal do Paranapanema region (state of São Paulo, Brazil) illustrates the model in agrarian reform settlements. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd

Influence of seasonal forage quality on glucose kinetics of young beef cows1

Extensive range livestock production systems in the western United States rely heavily on rangeland forages to meet the nutritional needs of grazing livestock throughout the year. Interannual variation in the quantity and quality of rangeland forage in the Northern Great Plains, as well as throughout much of the western United States, may play a pivotal role in how well grazing ruminants sequester nutrients in their tissues. This variation in forage quality may influence the ability of a beef cow to utilize dietary nutrients via changes in tissue responsiveness to insulin. Identifying specific periods and production states in which this phenomenon is manifested will provide insight into the development and implementation of strategic and targeted supplementation practices that improve nutrient utilization during times of nutritional imbalance and may improve the lifetime productivity of grazing range beef cows. A 2-yr study was conducted to monitor serum metabolites, glucose kinetics during glucose tolerance tests, and forage chemical composition every 90 d in young cows (2 to 4 yr of age; n = 28). In yr 1 and 2, cows were managed on 4 pastures varying in size from 36 to 76 ha in yr 1 and 49 to 78 ha in yr 2. Regardless of year, cow age, or cow physiological status, the main factor influencing glucose half-life was season of the year (P = 0.02). Effects of season on glucose half-life closely followed assessments describing forage quality, with glucose half-lives of 46, 39, 43, and 51 +/- 3.9 min for May, August, December, and March, respectively. Elevated glucose half-life during seasons in which forage quality is of lower nutritive value indicated that tissue responsiveness to the actions of insulin followed seasonal changes in forage quality. Glucose half-life tended (P = 0.09) to decrease between May and August, increased (P = 0.04) between December and March, and showed a tendency (P = 0.10) to decrease in seasons of greater nutrient density (May and August) compared with seasons of lower nutrient density (December and March). Seasonal changes in serum metabolites were also observed and corresponded with changes in forage quality. The results support our hypothesis that as the season progresses and forage quality declines, maternal tissues become less responsive to insulin, indicating that targeted supplementation with glucogenic precursors during these seasons of nutritional stress may improve cow performance.

Animal welfare issues associated with extensive livestock production: The northern Australian beef cattle industry

The animal welfare issues faced by the northern Australian beef cattle industry are similar to those faced by extensive livestock production industries in other countries. However, northern Australia is characterised by climatic extremes and large areas/distances and these factors, together with low management inputs, mean that the industry faces significant challenges to assure high standards of animal welfare. In this review, the following issues are discussed: behavioural restriction; ‘natural disasters’; nutrition; health; a number of aspects relating to human–animal interactions, particularly mustering (gathering/rounding up) and moving cattle, and the consequences for welfare of the timing and frequency of handling; ‘surgical’ procedures; identification; transportation, including live export; and predation. The use of cattle adapted to the northern Australian environment alleviates many potential welfare problems. In addition, significant improvements to animal welfare could be made very quickly with a few straightforward management changes, such as improved planning for extended dry periods and drought; wider use of conservative stocking rates and supplementary feeding; broader implementation of vaccination programs; and greater implementation of weaner training programs. Further, a dramatic improvement for very large numbers of cattle could be made through the selection and use of polled genotypes to eliminate horned cattle. Research from Europe suggests that current Australian recommendations for the duration of land transportation journeys may be excessive and could compromise welfare, but further research under northern Australian conditions is required. Research and development is also needed in non-invasive alternatives to castration and spaying, but in the meantime the welfare of males could be improved by castrating earlier in the animals’ lives. However, it is acknowledged that this would require major changes to current cattle management practices. Further research and development is required in relation to animal handling, and in particular the type, timing and frequency of experiences with stockpeople and also, on the assembly and sea transportation of cattle. Finally, a moral question exists as to whether cattle should continue to be exported to a particular country for which there is strong evidence of inhumane treatment.

Property Rights and Land Use Change: Implications for Sustainable Resource Management in Borana, Southern Ethiopia

ABSTRACT The Borana rangelands occur in a semi-arid area in southern Ethiopia, characterized by extensive livestock production. The area is a valuable source of livestock that generates income and livelihoods for large numbers of rural dwellers, and export earnings for Ethiopia's fragile economy. Despite the region's high ecological potential vis-à-vis livestock production, the area is still in a crisis today with limited success of development interventions, due to increasing pressure on the rangelands—appropriation of land by private individuals, with aggravated impacts of droughts, emerging conflicts and destitution. These trends are hypothetically attributed to various factors, including climatic, demographic and market forces. The paper utilizes data from forty pastoral communities in the area to identify the causes of these trends and potential consequences on rural livelihoods. The study infers that the Borana pastoral system is in transition, with evidence of departure from traditional pastoralism to a semi-sedentary system with increasing reliance on crops and private grazing. The semi-arid nature of the area-aggregate mean rainfall between 300 mm and 900 mm per annum-creates a concern about the capacity of the area to support a fully privatized system on a sustainable basis.

Model based impact analysis of policy options aiming at reducing diffuse pollution by agriculture—a case study for the river Ems and a sub-catchment of the Rhine

In this paper an integration of the agricultural economic model RAUMIS with the hydrological models GROWA98 and WEKU is presented. The focus lies on an area wide, regionally differentiated, consistent link-up between the indicator “nitrogen balance surplus” and nitrogen charges into surface waters. The model network is used to analyze the status quo situation in the year 1999 for two river catchments in Germany that feature very distinct natural and socio-economic conditions. Regarding agriculture, the study areas include regions with specializations in cash crops, in intensive livestock featuring high nitrogen surplus, and extensive livestock production on permanent grassland. Due to regionally varying hydrological conditions quite different shares of agricultural nitrogen surpluses ranging from 25 to 92% enter surface waters. Furthermore, impacts of alternative nitrogen reduction measures namely a limitation of livestock density and a tax on mineral nitrogen are quantified. Measures of the nitrogen reduction potential and costs in terms of agricultural income forgone are taken into account in the assessment. Results regarding the effects of restricting the livestock density or tax mineral nitrogen highlight that the mitigation of diffuse water pollution problems requires regionally tailored measures.

Policies, Interventions and Institutional Change in Pastoral Resource Management in Borana, Southern Ethiopia

The Borana rangelands of Southern Ethiopia are characterised by extensive livestock production under a communal land‐use system that has evolved in response to variable rainfall and uncertain production conditions. However, the last two decades have witnessed an increasing privatisation of rangelands for crop production and private grazing. The results of a quantitative assessment are used to develop a framework for assessing the drivers of change and their long‐term implications. It is concluded that certain national policies have resulted in conflicts of authority between traditional and formal systems, creating an avenue for spontaneous enclosures, associated conflicts and decreasing human welfare.

Drifting Rhinos and Fluid Properties: The Turn to Wildlife Production in Western Zimbabwe

This paper presents and analyzes a number of tensions that arose in the shift from extensive livestock production to wildlife ranching and tourism in a dispersed community of white farmers in western Zimbabwe. It sketches the broader context of that shift and considers some of its effects, including those on the small (black)farmers of neighbouring Communal Areas. The tensions highlighted and manifested between the ranchers of Mlilo include the necessary movement from a characteristic view of wildlife as ‘vermin’, destructive of the conditions for livestock (and crop) production, to an appreciation that they are an exploitable and valuable resource (‘ecological capital’); and how inherited views and practices concerning the boundaries of private landed property are subverted by the demands of wildlife ranching.

Local Determinants of Coypu Distribution along the Lujan River, Eastcentral Argentina

The coypu, or nutria (Myocastor coypus), is a semiaquatic rodent intensively harvested for fur and damage control. We conducted a survey along the Lujan River in Argentina to determine environmental factors affecting the distribution of coypu in its natural range. In each of 82 600-m transects randomly assigned along the river, we recorded the presence of coypu and habitat characteristics related to attributes of the river, nearby vegetation, and human activity. Coypu distribution was positively related to availability of grasslands used for extensive livestock production and negatively related to local human perturbations. Lowland prairies would provide an abundant and stable source of food to coypu, which could be used as a profitable natural resource in low productive areas of the Pampas region.

Recent Trends and Implications of Group Ranch Sub-Division and Fragmentation in Kajiado District, Kenya

The Kenyan Government introduced group ranches in Kajiado District in the 1960s. They were aimed at addressing the problem of overgrazing and land degradation, said to be occurring in the pastoral arid and semi-arid areas, by converting communal to group tenure.This was expected to encourage the Maasai nomadic pastoralists to confine their livestock within ranch boundaries and reduce their livestock numbers. Although group ranches in Kajiado failed to meet these expectations, they secured the Maasai's traditional land against alienation by non-Maasai. Thereafter, the Maasai continued using their land along traditional lines, which is increasingly being recognized as the most efficient and sustainable use. Group ranch sub-division into individual plots in Kajiado began in the 1980s with government support. Further fragmentation of plots and sale, in many cases to non-Maasai, followed sub-division. Average plot sizes have decreased, while the number of fenced properties and the levels of cultivation have increased. Due to sub-division, the Maasai are gradually losing their best land and are being pushed into the drier areas. Sub-division will threaten continued extensive nomadic livestock production by decreasing mobility and the carrying capacity of group ranch land, increase the potential for land degradation and crop failures, and interfere with traditional wildlife migration patterns.

Effects of herbivory on the production ecology of the perennial grass Leptothrium senegalense (Kunth.) in the arid lands of Northern Kenya

The graminoid layer forms an important forage resource for the extensive livestock production system of northern Kenya. However, in recent years, increased grazing pressure resulting primarily from exogenous influences has had severe impact on this very basic resource. The result is land degradation and a threat to the very existence of the nomads and their herds. To assess this impact, investigations were conducted on the perennial grass Leptothrium senegalense, to determine its production in relation to grazing pressure. Peak standing aboveground production was 0.2–46.8 kg/ha and 16.7–256.7 kg/ha on grazed and protected sites, respectively over a 3-year period. Rainfall also influenced production on the protected and seasonally grazed sites. The direct effect of grazing was a reduction in plant size. Based on height measurements, 70.6–78.2% and 85.3–100% was estimated to be removed by seasonal and year-long grazing, respectively. Simulated defoliation confirmed that grazing had its most significant impact on residual mass and reproduction capacity, leading to a reduction in the survival fitness of this species. Results also indicated that production of L. senegalense is water-limited, and that water stress may interact with intense grazing to limit its production and recruitment success. It is suggested that to optimise yield to grazers while ensuring reproductive success, grazing should be moderate to leave stubbles of about 15 cm. At this stubble height, adequate residual mass necessary for regrowth is also assured. In the light of this study, absence of L. senegalense can be considered a bio-indicator of overgrazing in the aird lowlands of the Rendille ecosystem.

A Decision Support Approach to Sustainable Grazing Management for Spatially Heterogeneous Rangeland Paddocks.

Public concern for the way land resources are used has led to the introduction of legislation in several Australian States requiring the demonstration of sustainable use of the pastoral resource. However, no practical system of appraisal of sustainability in grazing management systems exists. The common situation facing decision-makers at policy and enterprise levels is one of inadequate, unobtainable or inappropriate data, or systematic indeterminacy. This necessitates erring on the side of caution, through an adaptive integrated approach to decision-making. Such an approach requires: (i) an understanding of the key processes that govern the interactions between livestock, plants, and heterogeneous landscape systems; (ii) the identification of indicators of potential problems in these systems at spatial and temporal scales relevant to human use and management; and (iii) the availability of effective tools to evaluate management options in terms of their risks to the sustainability of the grazing land resource, and the profitability of production. This paper describes a decision support approach to improving our understanding of the complexities of grazing management systems. The paper first proposes an integrated framework for a decision support system (DSS) for evaluating the sustainability of grazing management in terms of the risk of changes to the vegetation and soil resource, and the profitability of production. It then examines an application of a DSS approach, called Landassess DSS, to the tropical woodlands in northern Australia, and discusses the broader implications for sustainable management of extensive native pasture livestock production systems.

An integrated approach to assessing the farm and market level impacts of new technology adoption in Australian lamb production and marketing systems: The case of large, lean lamb

New technology adoption is an important source of productivity gains in Australia's extensive livestock production systems because of the opportunities it offers producers to achieve sustainable cost reductions. Widespread technology adoption which leads to permanent production increases can be expected to have industry-wide effects because of the competitive nature of the Australian livestock industries. Assessing the potential economic benefits of new technology adoption therefore requires the use of a model which considers both the farm and market components of these industries. This paper describes the development of such a model and its ex-ante application in assessing the benefits of a new technology programme in Australian lamb production. Based on parameters derived from the model's farm and market level components, the introduction of this technology was found to offer significant annual benefits to both Australian lamb producers and lamb consumers (of between $4 and $30 million) according to several assumed market scenarios for the product.

The identification and evaluation of disease constraints for extensive livestock production systems

AbstractThe types of constraint caused by disease on extensive livestock production systems are described. Various approaches by which these constraints may be identified, quantified and evaluated are proposed and the advantages and disadvantages inherent in these different approaches are discussed.