|Sustaining the Future. Economic, Social, and Environmental Change in Sub-Saharan Africa (UNU, 1996, 365 p.)|
|Part 3: Environment and resource management|
|Agricultural development in the age of sustainability: Livestock production|
Livestock production, productivity, and feed resources
The effect of government policy on livestock production
Summary and conclusions
The livestock industry is an economic enterprise and can also be considered as a "survival enterprise" for millions of herdspeople throughout tropical Africa, especially in the arid, semi-arid, and subhumid areas. Among the multiple roles of the livestock industry, food production and gainful employment are the most important. Over 12 million people in West Africa, of whom over 3 million are in Nigeria, depend primarily on livestock for their survival, while over 70 million people in the same region depend on livestock and livestock-related enterprises for their livelihood (Nuru 1982, 1983; McDowell and DeHaan 1986). One-third of the African continent's livestock population is in West Africa.
How can the African continent, particularly the Sub-Saharan region, increase its livestock product production to meet the everincreasing demands of its people now and in the future, using all available natural resources, with no or minimum environmental degradation? Above all, how may the environment be preserved or sustained for future economic development when major environmental constraints such as drought and erosion could retard future progress in development?
Land degradation (soil erosion), drought, desert encroachment, etc. pose a significant threat to the use of land for crops and livestock production, especially in the arid and semi-arid zones where agricultural activities are the main occupation of the people of Sub-Saharan Africa. To prevent further deterioration and to increase the productivity of food animals, it is necessary to act now.
Because of its economic and social significance, the livestock enterprise must be considered or viewed holistically: the animal, its environment, and productivity. It is the interaction between the physical environment and the animal's genetic make-up that determines productivity and even the survival of both animal and plant species within a given ecosystem. In this holistic approach, human factors such as culture and social and economic status as related to other production factors are also important because they influence productivity. Most African cattle are still in the hands of pastoral livestock owners - the Fulanis, Shuwas, and Fulas in West Africa and the Masais in East Africa. Their husbandry methods are indigenous and based on lowinput systems. However, their survival strategy is influenced by seasonal migration to areas with optimum forage resources to feed their animals. This has an effect not only on animal productivity but also on the ecosystem.
When considering ecological stability and increased animal protein production from domestic animal species, the two main natural factors of production are:
· the animals - in this case the ruminants but, to a lesser extent, the monogastrics;
· the land and climatic conditions.
Other factors of production are credit facilities, marketing, and the socio-economic status of the herd owners. These factors do not have a direct effect on environmental degradation, whereas the cultural practices in the husbandry system do.
The animal species: Contribution and spatial distribution
Among domestic animals, the ruminants - for example, cattle, sheep, and goats - form the largest number and are of paramount social and economic importance in tropical Africa. There are several reasons why ruminants should be given special attention when considering ecological change in Sub-Saharan Africa.
First, they supply the bulk of livestock products. The ever-increasing demand for these products owing to increased human population and better health education justifies greater attention to animal production if the continent is to avoid a huge animal protein deficit.
Secondly, because of the large population of ruminants and their dependence mainly on global grazing, large areas, especially in West and East Africa, are in danger of irreversible soil degradation and desertification. Ruminants, though not the sole factor in these ecological disasters, contribute through overgrazing and subsequent soil compaction and wind erosion. Their survival is based on genotype adaptability to the fragile environment and the vagaries of climatic conditions.
Cattle and a few other large ruminants constitute 83 per cent of food animals and produce over 45 per cent of meat products and over 90 per cent of available domestic milk supply. Sheep and goats (medium-large stock), on the other hand, constitute 15 per cent of the total number of food animals and contribute about 35 per cent of meat, as well as fibre. As of 1990, 187.8 million cattle, 205.0 million sheep, 173.9 million goats, and 13.6 million pigs were estimated to be in Africa (FAO 1991: 191 and 194). Of these, approximately 178.6 million cattle, 162.4 million sheep, 157.8 million goats, and 13.5 million pigs were in Sub-Saharan Africa. Sub-Saharan livestock produced 6.7 million metric tons of meat (slaughter weight), 14 million metric tons of milk, and 0.9 million metric tons of hens' eggs (FAO 1991: 199-226).
However, there is a higher elasticity of demand than of supply. In West Africa alone, a deficit of 2-4 million tons of meat and 6.5-9.0 million tons of dairy products is envisaged by the year 2000 (McDowell and DeHaan 1986). Table 12.1 shows the distribution of some animal species in Africa compared with world estimates These animals are not evenly distributed across the African continent. As shown in table 12.2, for the West African region, the semiarid zones contain the largest number of ruminant species (16. TLU1) compared with the arid (10.8 TLU), sub-humid (6.2 TLU), and humid zones (4.3 TLU) (Jahnke 1982; McDowell and DeHaan 1986). In terms of stocking density (table 12.3), the arid zone has a low livestock per unit area (2.7 TLU/km2) compared with the semiarid zone (11.1 TLU/km2). Thus the semi-arid areas have more animals per km2 but this is possible because of higher land productivity The highest number of ruminants is found in this zone in West Africa Although the sub-humid and humid zones have greater forage potential, the climate and prevalence of typanosomes limit the use of these two zones for raising ruminant livestock, hence the very low numbers per unit area (2.2 TLU/km2) in the humid zone.
Table 12.1 Livestock numbers in Sub-Saharan Africa, West Africa, and the world, 1990
|World (m. head)||1,279.3||1,190.5||557.0||856.7|
|Sub-Saharan Africa (m. head)||178.6||162.4||157.8||13.5|
|% of world||14.0||13.6||28.3||1.6|
|West Africa (m. head)||42.8||42.2||59 5||6.4|
|% of SS Africa||24.0||26.0||37.7||47.4|
Source: FAO (1991).
Table 12.2 Human and livestock distribution in western Africa, 1979
|Area (km2 million)||4.0||1.5||1.6||1.9||9.0|
|Agricultural population (m.)||6.9||36.1||16.1||31.1||90.2|
|Cattle (m. head)||9.0||21.6||6.2||3.8||40.6|
|Sheep (m. head)||13.2||10.1||6.7||6.0||36.0|
|Goats (m. head)||14.8||19.2||11.8||8.7||54.5|
Source: Adapted from Jahnke (1982) by McDowell and DeHaan (1986).
TLU, Tropical Livestock Unit = 250 kg livestock body weight.
Table 12.3 Livestock densities in various ecological zones of West Africa
|Agricultural population density (n/km2)||1.7||24.0||10.1||16.4|
|TLU per agricultural capita||2.5||0.5||0.4||0.1|
Source: McDowell and DeHaan (1986).
TLU, Tropical Livestock Unit = 250 kg livestock body weight.
The role of monogastric food animals - poultry and swine in particular - in increased animal production potential in Sub-Saharan Africa cannot be underestimated. These animals compete with human beings for available grain, especially maize and sorghum, which are the staple food of the African peoples. However, these species can have greater meat and egg turnover in a relatively short time. Although they are intensively raised on restricted land areas, their contribution to environmental problems can be great. Air pollution owing to odour from pig and poultry houses can be a nuisance to nearby inhabitants. Sustainability of productive capacity of these animals is more easily accomplished, especially with modern trends in housing and feed technologies. Recycling of manure by spreading it on arable cropland ensures increased crop production at reasonable cost as well as environmental conservation.
The land resource, climate, and production systems
Large areas of African soils are said to be fragile and are classified as of low productive capacity in many countries within the continent. Most of the available land for agricultural production is located within fragile and ecologically sensitive regions, e.g. tropical rain forest, arid savannas, and the drought-prone Sahel, where a large proportion of the cultivated area is not compatible with sustainable agriculture. Land-use systems are usually based on incomplete knowledge of the status of the land resources of the various areas (Anande-Kur 1992). These factors must be borne in mind because knowledge and information about the land resources of a given ecosystem for a particular production - arable or livestock - are essential, as can be seen when related to the stocking density and effect on the environment.
For the purpose of this paper, I am more concerned with the ecological and agro-climatic zones in Sub-Saharan Africa as they relate to livestock enterprises and to the sustainability of all production systems.
The ecological zone classification is based on the number of growing days, i.e. days with rainfall. Thus the arid zone has 0-90 days of rainfall, the semi-arid zone has 90-180 days, the sub-humid zone has 180-270 days, and the humid zone has rainfall for over 270 days annually (McDowell and DeHaan 1986). It is the agro-ecological zones that determine both crop and livestock production in a given zone. The intensity, frequency, and distribution of rainfall influence biomass production in a given area, and hence are a determinant factor in the carrying capacity of the land for the purpose of raising livestock. In general, the majority of ruminants in Sub-Saharan Africa are raised on range-land where feed resources are mostly naturally growing grasses and legumes but with occasional supplementation with leaves of shrubs and trees. The husbandry systems are either nomadic, semi-nomadic, or settled. Stock owners with large herds often practice full pastoralism, while those who are agro-pastoralists often have small herds and are sedentary or settled. The global grazing habit of a large number of domestic ruminants has a detrimental effect on the environment, especially as the stocking density can be very high in marginal grazing areas (table 12.3). Because of the high stocking density and fewer watering points in these zones, erosion due to constant trampling around water points can be an added detrimental effect of overgrazing.
The effect of seasonality on ruminant livestock production is also very important. In the mid wet season, forage biomass is higher in quality and quantity, with crude protein up to 9 per cent in most of the native grasses. Natural grasses and legumes are rich and highly digestible at this period. As the dry season sets in, the protein level drops and the roughage quantity increases. There is an increase in lignin content and voluntary intake decreases. This is a poor feed resource, resulting in weight loss and decreased fertility and milk yield for up to 4-5 months of the year. The severity and duration of low-quality feed differ from one country to the other within the region. To worsen the ecology and its available food resources further, there is widespread annual burning of native grasslands, thereby drastically reducing the amount of forage on offer. Indeed, it has been observed that a combination of these factors - low-quality roughage and bush burning, which reduce the biomass available in quantity and quality - could lead to weight losses ranging from 300 to 400 g per head per day for cattle (Zemmelink 1974) and up to 15 per cent of body weight in sheep (Otchere et al. 1977).
In the arid zone, nomadism and transhumant systems of livestock production prevail. In these systems, high mobility for global grazing habit is the most efficient adaptation to the erratic rainfall. Migration from one area to another in search of good quality and quantity of feed and water is the rule. Transhumant or semi-nomadic systems have a home base, although they too are very mobile, with the majority of animals and the family away for several months and only 2-6 lactating cows left at the base to provide milk for sale and for the utilization of the aged parents left behind. Feed from crop residue provides the main energy source during and shortly after harvesting periods.
In all the zones, the main constraints on feed resources are the destruction of perennial tree cover for firewood, bush fires caused by hunters and livestock rearers, and overgrazing. These man-made constraints often lead to serious degradation of the range resources and in some cases to an irreversible process of desertification, especially in the Sahel zone. The sub-humid zone (SHZ) has a high potential for ruminant production because of the high rainfall and vast land area for forage production. In Nigeria, the SHZ contains only 19.59 per cent of the total national livestock units (Otchere and Nuru 1988). This low percentage of TLU in the Nigerian SHZ is attributed partly to tse-tse infestation and high humidity.
In a number of countries, Nigeria in particular, there are governmental policies on livestock production as well as on the environment. On livestock, the government is concerned with the grazing rights of stock owners in forest areas. The Grazing Reserve Law of 1964 in Nigeria is a good example. Shelter belts have been created to prevent desert encroachment. Federal or national environmental protection agencies have been set up by some governments within the region. A lot more emphasis is, however, placed on environmental pollution from oil spillage and on drought prevention rather than on natural herbage resource conservation. In many countries, the land tenure system is a major constraint on range conservation or increased production. Policies on the land tenure system and land use are mostly to the advantage of city dwellers and a few enlightened farmers. In many countries, the laws are hardly obeyed and people (hunters, etc.) are rarely penalized. In order to achieve their objective, such laws and regulations must be not only technically sound but also socially acceptable.
It can be seen that the present livestock production, based on global grazing husbandry systems, ecological destruction through bush fires, and overgrazing due to high stocking density in areas where feed or water resources cannot support the number of animals, does not augur well for present and future productivity and sustainability.
What then are the solutions to ensure sustenance of the ecosystem and its herbage and tree shrubs cover and of the grazing livestock species for the future economic development of Sub-Saharan Africa?
Livestock production is still very much based on traditional systems in Sub-Saharan Africa, even in such agriculturally advanced countries as Nigeria, Zimbabwe, or Egypt. One would have thought that, with a large number of livestock research institutions and faculties of agriculture and veterinary medicine in the region, a newer and more modern approach to livestock enterprise would have provided the answer for future productivity and the sustainability of both animals and the environment. It is true that old habits die hard and, therefore, the traditional herding system will continue in many African countries.
It will not be possible drastically to change the cultural and socioeconomic status of the livestock producers for at least another decade. It has, however, been shown that their production systems are more efficient in terms of livestock product yield per animal per unit area, probably because of their husbandry knowledge and complete devotion to their vocation. Large-scale farms with modern techniques of production are not the only way to sustain productivity. They are too capital and labour intensive to guarantee a profit compared with the low-input systems of traditional owners. A lot of large-scale livestock and arable farmers have failed in many countries, Nigeria being a good example. Indeed, it has been shown that in Zimbabwe, Botswana, Kenya, and Mali the contribution of communal livestock production to the national animal protein yield is greater than that from commercial ranching enterprises in terms of kg of protein production per hectare per year (Barrett 1992). For these and other reasons, our attention must be primarily focused on how to improve the traditional systems, to introduce simple and adaptable innovations and techniques to enhance productivity and yet protect the environment from being abused to the extent of irreversible degradation.
Suggested solutions for sustaining the productivity of both the livestock and plant species for future development are therefore centred on the following strategies:
1. improved animal genetic resources to meet future needs;
2. improved nutrition;
3. improved management;
4. government policies and commitments;
5. active participation by the private sector.
Improved animal genetic make-up
Modern ideas about animal production are mostly based on: the use of big-engineering to improve on the genetics of various animal species for higher output, embryo transfer, and immuno-genetics; artificial insemination and cross-breeding for quick genetic gain in heterosis; improvement of reproductive efficiency through the use of hormones and drugs to improve fertility rates. Developments in breeding animals with increased resistance to diseases and pests as well as in animal health and disease control through vaccine production are major contributions. Recombinant DNA technology has of recent years offered remarkable opportunities for restructuring animal phenotypes and ability to withstand viral and bacterial diseases. Cross-breds, if so adopted, would yield more meat (through faster growth) and higher milk output in a relatively short time. The goal of all these techniques is to produce a biologically efficient animal species for each ecosystem. However useful these techniques are, they are too advanced to be used by the present-day resource-poor subsistence farmers in Sub-Saharan Africa, but could be of advantage in future to conserve the ecosystem and yet increase livestock production to meet the needs of the year 2000. For the next decade, emphasis should be on animal health through effective control of "economic diseases" such as gastroenteritis due to helminth parasites, streptothricosis, trypanosomiasis, and other chronic diseases that give rise to wastage owing to abortion, infertility, stillbirths, and unthriftiness, and even deaths.
Improved nutrition is the key factor. One way of achieving it is through increased crop yields, because grains and tubers are used to supplement natural grasses. Other methods are: effective management and utilization of natural pastures; feed resources conservation; and use of arable crop wastes.
At present, the global grazing orbit is declining owing to physical development (roads, new HQs, etc.) and the expansion of cultivated land as a result of large agricultural schemes. Therefore, better and more efficient management of range land is essential, e.g. controlled grazing, controlled stocking density, avoidance of bush fires, range reseeding, and water supply.
In order to conserve feed resources, silage and hay could be made from high-quality grass and legumes, and agricultural crop residues such as groundnut and cowpea tops could be conserved when the nutritive value of the plants used is high. Unfortunately, the inputs for such technology (tractors, bailers, etc.) are hard to come by for many peasant livestock farmers.
Within the past two decades, the mechanization of agriculture for crop production has contributed immensely to increases in cereal crop production and therefore in crop residues. However, it must be noted that mechanized farming has also physically contributed to soil degradation, resulting in deterioration of the soil structure and compaction of the subsoil (Anande-Kur 1992). These effects in themselves render the soils prone to erosion. The integration of livestock and crop production systems on a given land area can improve soil fertility through the output of organic manure by the animals and the more effective utilization of crop residues.
The utilization of crop residues for increased animal protein production has received greater research attention within the past decade because of the higher quantities of crop residue, especially from sorghum, maize, and millet, and partly because of the astronomical increase in the prices of agricultural by-products such as wheat and maize offal residue used for livestock feed, groundnut and cotton seed cake, and brewers dried grain. The importance of crop residue in the dry season feeding of ruminants in the Northern Guinea Savannah has long been recognized. Van Raay and de Leeuw (1971) estimated that crop residue grazing accounts for 85 per cent of total grazing time from the harvest period in December, declining to 40 per cent in February in the Sudan Sahel zone of Nigeria. Alhassan (1985) estimated that for every kg of grain harvested, there are 4 kg dry matter of straw from sorghum, 8 kg from millet, and 4 kg from maize straw. From table 12.4 it can be seen that approximately 16.4 million metric tonnes of sorghum straw and 23.2 million metric tonnes of millet straw were available in Nigeria in 1980/81 from 6.1 million hectares of sorghum and 4.5 million hectares of millet, respectively. This may apply to other countries in Sub-Saharan Africa where these crops are grown on a large scale. By treating this straw with non-protein nitrogen sources or chemicals (e.g. urea, ammonia, and sodium hydroxide) the lignin content will be degraded and the feed value and palatability enhanced. If animal feed is supplied in this way, further destruction of the ecosystem by way of bush fires for early grass growth and overgrazing when feed resource is scanty can be prevented or minimized. Here again, education of the stock rearers about the need to settle and adopt such simple technologies is essential. Other agricultural by-products with great potential for animal feed include sugarcane tops, molasses, bagasse, discarded cocoa beans, pineapple tops, and other rejects.
Table 12.4 Estimated areu sown to sorghum and millet and their grain and straw producffon for venous cropping years
|Area||Grain production||Estimated straw||Area||Grain production||Estimated straw|
|(ha m.)||(m.t)||(m.t)||(ha m)||(m.t.)||(m.t.)|
Source: Nuru (1986).
It can be seen that, for optimum resource usage, there is an urgent need for an integrated approach to livestock development for increased product availability at reasonable or affordable prices and enhanced natural resource management and conservation.
Similarly, the use of microbes has greatly enhanced our knowledge about the production and utilization of better nutrients to feed various species of animals for a higher output of meat, milk, and milk products. In addition, modern trends in production make use of anabolic steroids - a combination of progesterones, oestrogen, testosterone, and zeasolone (plant origin) - as feed additives to promote faster growth and therefore higher output; growth hormones to increase milk production in lactating cows; and ionospheres (antibiotics) and coccidiostats in poultry. These drugs are mentioned only in passing here, because the level of education, socio-economic status, and acceptance of these new techniques by the majority of livestock producers cannot at present be guaranteed. Only a few enlightened farmers in southern Africa are able to use these technologies. More appropriate and simple technological innovations therefore need greater emphasis.
Improved management techniques
Change from a free-range production system to an acceptable marketoriented and sedentary system could be considered. Most of the destruction of ecosystems is due to bush burning, overgrazing, and lack of adequate water points. A more sedentary husbandry system with higher input and higher output could be desirable in some agroecological areas. This would not be easy in the arid zone, but it would be possible in the semi-arid and sub-humid zones. In the arid zones, a reduction of livestock numbers in keeping with the carrying capacity of the land is desirable. Agro-pastoralism is a solution in some areas where there is adequate rainfall. This is the emerging trend in the sub-humid zone of Nigeria, where more and more pastoralists are settling (ILCA 1979; Otchere et al. 1985). In this way, the concept of integrated farming systems can develop to great advantage. In the Congo, and other densely forested countries, the use of typanotolerant breeds of animals is now more emphasized. These animal species are not only adapted to the environment but also more productive in such areas. It must be noted, however, that sedentarization and its acknowledged benefits can be achieved only through a dynamic and workable land tenure system that is the responsibility of the government.
According to Harrison (1987), forestry has been considered separately from agriculture and livestock. Foresters view farmers and herders as vandals and destroyers of forests, while peasants see foresters as policemen who exclude them from land that was traditionally theirs to control and use. Farmers view tree planting as an alien activity carried out by unpopular professionals. Forestry nevertheless has a crucial role in farming and pastoralism in Africa. There is a need to integrate forestry fully into crop and livestock production in order to sustain agriculture in a stable ecosystem in the future. The Grazing Reserve Law in Nigeria is worthy of emulation by other countries. Suitable trees will provide fodder for animals at the end of the dry season and the beginning of the rains when feed is scarce. The most crucial role of appropriate forest trees would be the recycling of soil nutrients in an environment in which heavy rains leach nutrients below the reach of crop roots and the maintenance of soil organic matter in an environment in which high temperatures break down organic matter very quickly. A promising approach to agro-forestry to sustain crop and livestock production is alley farming. Suitable multi-purpose trees that provide abundant fodder or mulch from their leaves, fuelwood and stakes from their stems, as well as the ability to fix nitrogen are greatly recommended. At the moment, trees such as Leucaena leucocephala, Gliricidia septum, and Sesbania seban, among others, have been found suitable. There is, however, the need to increase the number of species that meet the requirements.
With the current increase in crop production through massive landclearing in many countries in Sub-Saharan African, coupled with the growth of population and hence the physical development of more and larger towns and cities (urbanization), the land-use pattern is constantly changing and less land is available for crop and livestock production.
Intensive production systems and the use of crop residues and agricultural by-products are thus further emphasized. Because of the limiting factors on global grazing, which are even more likely to be a problem in the year 2000 if livestock and human population growth are not restrained, the need arises for sedentarization and pasture establishment if there is to be enough animal protein and at the same time the natural ecosystem is to be conserved. Technically, scientists have developed suitable pasture plants to meet the variations of the agro-ecological zones in Sub-Saharan Africa. The grasses and legumes required include Digitaria spp., Buffel grass, Guinea and Rhodes grasses, together with Stylosanthes, Centrosema, and other varieties of legumes. It will require social and cultural changes amongst the nomadic and livestock owners if they are to adopt the technologies that have been developed and to treat livestock ventures as viable commercial enterprises not just a way of life. In this respect, several African governments have a lot to do as regards land tenure systems and the provision of assistance in the acquisition of infrastructure and credit facilities for a profitable future livestock industry.
As part of the new technology in animal husbandry, improved pastures produce more dry matter of high nutritive value and lead to greater animal productivity than do native pastures. To date, the traditional African livestock farmer has yet to adopt these new techniques. Throughout Sub-Saharan Africa, grazing land is communal; only a few private ownerships exist. Improvement of the range by individual stockowners by oversowing with legumes and by fertilization is not advantageous because grazing areas are for communal usage.
There must be more emphasis on the training of range and pasture specialists in order to achieve success in range improvement and conservation and in pasture establishment and effective utilization, and also to prevent further range degradation and to ensure increased livestock productivity.
Government policies and commitments
Government policies and programmes to assist herdspeople and the millions of people engaged in livestock enterprise need to take cognizance of the following:
(a) The land tenure system must be revised in some countries to make it easier for those who really need land to obtain it. The need to instill pride of ownership and willingness to invest in development is crucial because communal grazing is free and therefore unattractive for commercial livestock enterprise.
(b) Nomadic education as presently carried out in Nigeria is encouraging and worth emulating by other countries.
(c) The supply of sufficient manpower/experts, e.g. animal scientists, range managers, and technical staff, is essential. Most African universities are non-starters in the production of such specialists.
(d) Regulatory control of herd size and distribution to achieve ecological balance and avoid overgrazing needs policy attention. The encouragement of herd owners to move to the sub-humid zone in Nigeria, which is rich in feed resources, is a very slowly developing programme.
(e) Greater incentives to producers - marketing, credit facilities, technical supervision, subsidized inputs, etc. - are essential.
Active participation by the private sector
Private sector participation in the primary production of livestock is highly desirable if the necessary output of livestock products is to be achieved in the future. Through this sector, environmental degradation can be minimized and increased productivity of livestock products ensured. So far, only in Zimbabwe, Botswana, Kenya, and South Africa are people engaged in modern commercial livestock production. The need to invest in the industry as a high-potential economic enterprise cannot be overemphasized if the future is to be safeguarded.
The demand for food of animal origin is growing much faster than production because of better health education, higher income per capita, and ever-increasing population growth. Yet, owing to the application of Structural Adjustment Programmes, many African countries are poorer than before and livestock products are beyond the reach of the ordinary person. Many governments in Sub-Saharan Africa will face serious problems in terms of food self-sufficiency and food security if immediate and adequate measures for sustainability are not taken.
The two most important resource bases in livestock production are the animals and the range land on which they depend for survival. The genetics of the various species of animals and plants and their interaction within a given ecological zone form the basis of their productiveness or otherwise. The ability to maintain the pace of economic development from these resource bases (since they are governed by external factors, e.g. climate, social, cultural, and economic status of herdspeople) is the focus of the concept of sustainability. However, for any given system one may wish to sustain more than one aspect of the system. For example, in livestock systems, genetic considerations may be just as important in the tropical environment as the feed resource base, in which case conflict can arise. Again, the concept of sustainability without consideration of social objectives or goals is meaningless in terms of future economic development. The herd owners' social objectives may not tally with the government policy objective in that the herd owners may be more interested in maximizing the numbers of their stock whereas the government objective may be sedentarization of the herd owners in order to be able to increase the productivity of the animal per unit area using available technologies in animal husbandry, including nutrition and herd health management. Sustaining a given subset of a system therefore needs to be taken more seriously while thinking of overall future economic development gains.
Ruminants have a greater effect on ecosystems than other animal species. They are numerous and provide substantial quantities of animal protein. However, their production is based on age-old husbandry systems, which need to be gradually modified in order to meet the needs of consumers. A reduction of animal numbers in accordance with the resource capability of the land is essential. The various governments in Sub-Saharan Africa must try to achieve this through legislation and inducement packages. In addition, the sedentarization of nomads and the acquisition of land (i.e. a change in land tenure systems) can greatly increase the adaptation and use of new techniques in animal production systems.
The present poor system of livestock production of the majority of herd/flock owners should not be a deterrent to exploring future possibilities. In this context, therefore, one could stress the need to "domesticate" the environment so that it can cope with the production effort, especially for monogastrics. The alleviation of environmental stress through genetic improvement, hormonal regulation, feed intake, and control will be an important consideration for future needs.
Research into optimum environments for livestock will need to be addressed; for example, poultry houses with relative humidity, temperature, etc. controlled to make them conducive to rearing have led to higher output in Europe, the USA, and other countries. Comfort, productivity, and the economics of poultry and swine production will be the rule rather than the exception even in tropical environments. These are to be achieved through environmental control and animal welfare considerations.
Owing to space constraints, I have not considered the role of wild life in the preservation of ecosystems in this paper. They form part of Africa's cherished biodiversity and their significant role in the supply of bush meat, especially to rural people, needs no emphasis. However, with intensive hunting for game, they are declining in number, and the present number of herbivorous species is not a threat to the ecosystem. Destruction by bush fire and the cutting down of young and old trees for firewood or the clearing of dense natural forests for agriculture pose more threat to the system and should be regulated for future animal protein production.
Government assistance through research and the development of specialist skills, e.g. range management, pasture expertise, and animal science, is of paramount importance to ensure future economic growth and development in the livestock sector if Sub-Saharan Africa is to meet the challenges of the future.
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