Description of typical situation
Pastoral systems are characterized by mobility, grazing of the natural vegetation as the main source of feed, and predominant use of communal lands. Herders move with their animals for feed and water to avoid diseases and to access markets. Examples of these systems are found in Sub-Saharan Africa (the Sahel, Horn of Africa), Central Asia (Mongolia) and high-altitude lands around the world. Various forms of pastoralism are distinguished: Nomadic pastoralism is defined as pastoralism with constant movement, and transhumance is pastoralism with seasonal movement often between well-defined territories. Pastoralists combining crop production at a homestead with the movement of livestock during part of the year are referred to as agro-pastoralists. Pastoral systems are found on grasslands of all continents. Herders move with species, such as reindeer, camelids, sheep, goat, and cattle in mountainous and arctic regions of Latin America, Europe, and Asia, where it is generally too cold for crop production. Most other vast grassland regions are found in tropical semiarid and arid climates, where it is too dry (most regions have < 1000 mm of precipitation annually) and too hot for crop production. So, pastoralist systems are land use systems adapted to conditions unfavorable for crop production.
For pastoralists, livestock have multiple functions: They are a store of wealth; a source of food, such as dairy products and meat; a source of draft power; a sign of social status; and a source of marketable commodities, including live animals and manure. Pastoralism is thus considered to be a livelihood strategy as well as a way of life as it completely determines the social and economic organization of the people involved and for many centuries has been an important cultural heritage of mankind. West Africa has a high number of pastoralists and will be presented as an example of pastoralism in this context. It is estimated that the world has approximately 120 million pastoralists of which 50 million reside in Africa, with 20 million living in West Africa. Since a sustainable herd size is approximately three to four cows per person, the livestock population in pastoralist herds is between 60 million and 80 million in West Africa. In West Africa, the transhumance system is the predominant form of pastoralism. The West African pastoralists generally graze their livestock (mainly ruminants and camels) on the savannah grasslands during the rainy season to benefit from the nutritious biomass and to avoid cropped areas which are mostly dedicated to agriculture and mixed crop-livestock systems. During the dry season, the availability and quality of grass in the savannahs become insufficient for livestock feeding, and herders move with their livestock to crop-producing regions to have them feed on the crop residues that remain on the land after harvest. This crop residue grazing has reciprocal benefits for the crop farmer as manure from the animals is deposited directly on the fields. This traditional symbiosis between pastoralists and crop farmers is presently confronting several challenges: reduced availability of grazing land due to the expansion of croplands, reduced access to croplands for dry season grazing because of intensified cropping (e.g. because of dry season cropping on residual water), loss of the value of manure as it is being substituted by synthetic fertilizers in intensified crop production, and reduced access to the corridors along which pastoralist move as a result of policies to curtail pastoralism, cropland expansion, and infrastructure expansion. International borders are also becoming increasingly difficult to cross for herders and their animals. As a result, crop farmers and pastoralists compete for the use of corridors, grazing lands, and croplands; conflict between them is common.
Common environmental issues
Generally, (agro-)pastoral systems are considered to be in balance with the unfavorable conditions and thus contributing to food security from very marginal lands. At the same time, pastoralist grazing is often mentioned as a risk factor for grassland degradation. Grassland degradation is observed as vegetation cover is altered (reduced or even entirely eliminated, or evolving from grass to shrub), and signs of soil erosion appear. Such degradation reduces production potential but also biodiversity, the amount of carbon stored in soils, and replenishment of aquifers. However, pastoralist herders generally take their herding decisions based on the availability and quality of the grassland vegetation to sustain their livestock’s needs. This results in a type of grazing management in which herders generally move to new grazing areas before the regenerative capacity of the vegetation is affected by the grazing. Nevertheless, in the case of land access restrictions and times of prolonged droughts, when herds gather around water bodies and watering points as a last resort for survival, severe local overgrazing may occur (Principles 2, 3 and 5).
In many dryland regions, watering points are dug as a water source for pastoral herds. This has affected traditional moving patterns in the sense that herds may stay longer around the watering points, increasing the pressure on grazing lands surrounding the watering points and the chances for overgrazing. This mostly occurs during prolonged droughts. During regular years, however, the vegetation beyond a radius of 1 km from watering points is generally not notably affected (Principles 2, 3 and 5).
Another environmental issue is the relatively high greenhouse gas (GHG) emission intensity associated with the pastoralist production of meat and milk. Livestock productivity in pastoral systems is low because of the variable- and often low-quality feeds, the high energy expenditure on walking and grazing, and the large herd sizes. Methane is the most important GHG emitted. Other contributors to GHG emissions, such as manure deposition on grasslands, land use change, manure storage and application in agro-pastoral systems, and fossil fuel use, are of marginal importance in pastoral systems. In addition, pastoralists tend to keep large herds as a coping strategy against prolonged droughts as the chances of animals surviving a long drought are higher for a larger than for a smaller herd. This coping strategy is associated, therefore, with higher emissions of overall GHGs. These higher emissions should, however, be attributed in part to the coping strategy and other services provided by the herd (e.g., transport and fiber) as opposed to the production of edible meat and milk products (Principles 2 and 3).
Common animal health issues
Over the course of millennia, (agro-) pastoralists have adapted to natural resource variability and climactic changes, contributing to food security from very marginal lands. Yet, pastoralists' livelihoods continue to remain dependent on living animals, which are subject to potentially catastrophic losses through diseases, stress, lack of accessibility to veterinary services, or resource scarcity. In dry-pastoral regions, livestock populations are especially susceptible to changes in environment. Pastoralists often face tough animal health decisions such as facing losses from migration (i.e. travelling long distances to receive veterinary services) or staying on sub-optimal land, which result in coping strategies that are complex, affecting animal health and welfare in a variety of ways. For example, risk of prolonged droughts can result in the keeping of larger herds, with the hope that a larger herd means more animals surviving, putting pressure on resources due to both size and longer recovery times. Since pastoralists greatly rely on mobility as a critical coping strategy, land access restrictions on top of grassland degradation/soil erosion can lead to losses. Stress resulting from poor animal nutrition, water scarcity, long distance walking, etc., can also lead to otherwise normal microflora becoming pathogenic to animals. Even in disease-free areas, the risks of livestock disease transmission by animal mobility of wildlife remains high, causing transmission of diseases to new places. A recent example is the transmission of peste des petits ruminants of small ruminants to saiga antelope, a critically endangered animal. Furthermore, periods of drought can cause herds to gather around water bodies and watering points, facilitating disease spread. Overall, containing infectious diseases in this context can be extremely challenging. (Principles 2, 3, 7)
The mobility of farmers and their herds has the double potential effect of exposing healthy animals to new viruses upon their arrival, introducing infected animals into disease-free areas putting at risk origin and destination countries, or just contributing to sustain pathogen transmission maintaining endemism. Places of animals gathering can be considered a doble-edged sword, as on one hand the animal mixing and contact is a risk factor for disease transmission of diseases amongst animal but also to human. Stress and crowding of animals can lead to unpreceded pressure on already marginalized land, which can then lead to large herds of poorly fed animals concealing subclinical pathogens. This can also lead to microbial resistance pathogen spillover to humans. Greater animal survival rates mean that pastoralists should de-stock to limit these negative impacts. This is particularly important when natural resources are the key limiting factor of herd sizes. Education for behavioral change and good market linkages with private sector engagement can help maintain a well-managed, effective herd size and thus avoid herd overstocking. (Principle 2, 7)
Ability to cope with disease risk for pastoralist communities is highly dependent on access to veterinary services. For example, an epizootic disease can quickly wipe out an entire herd before veterinary services are able to reach an area. This history of diseases devastating pastoral herds have led to quicker acceptance of modern veterinary medicine in many cases, with vaccinations and drugs allowing pastoralists to increase herd sizes. Disease control, such as well-intentioned, large-scale vaccination campaigns, once completed have often left the normal veterinary infrastructure unable to continue such services, having to allocate limited resources across large landscapes with differing disease threats. Furthermore, access to reliable cold chains in pastoralist settings presents a challenge, particularly for the stability of temperature-sensitive vaccines, as in the case of Rift Valley fever. This can leave pastoralists desperate for medicines and stimulates the evolution of extensive black markets for drugs-- many of which are of low quality, expired, or fake. This can also contribute to antimicrobial resistance (AMR). The use of inadequate or failing drugs can then lead to pastoralists skeptical of investing in the use of modern medicines or veterinary services. Access to adequate veterinary services and products, veterinary infrastructure and laboratories, as well as education and training remain critical to improving the sustainable livestock development for pastoralist communities. Due to changing disease threats and conditions across communities, a key challenge to address is locally adaptable veterinary services and health education. Other disease control measures such as movement restrictions, while they can effectively limit spread of contagious disease, create trade-offs between disease control and traditional mobility. Assessing contact patterns across pastoral areas is essential for understanding the spread of infectious diseases which can better allow for both disease control and mobility. A One Health approach for service delivery in this context can be particularly beneficial, with pastoralists living in close proximity to their livestock; the health of livestock is closely linked to the health of people. Innovative solutions can also play a big role in transforming and adapting veterinary services, such as taking advantage of mobile/internet networks where possible. Principles 2, 6, 7)
Pastoralists are usually highly knowledgeable about behavior and physiology of their animals, and often take great control and care over genetic resources and reproduction, often managing rare livestock breeds. There is increasing concern that these genetic resources- traits such as resistance to extreme climates or weather conditions- are disappearing due to introgression.
Thus, veterinary programs on disease control in pastoral systems must take into account consequences of overall animal-production systems (e.g.: social dimension impacts on mobility, reproduction strategies and genetic resources, increasing pressure on natural resources, etc.). (Principle 1)