J.E.O. RegeInternational Livestock Centre for Africa
P.O. Box 5689, Addis Ababa, Ethiopia
Abstract
Introduction
Agroecological zones and production systems
Distribution of small ruminants by agroecological zones
Special attributes of small ruminants
Role of small ruminants
Small ruminant genetic resources of Africa
Performance potential of indigenous breeds
A case for evaluation and conservation
ILCA/FAO plan of action
References
The accelerating demands of a growing human population and the pressures of economic development are affecting the security and survival of many indigenous African breeds. Until now, these breeds have been a stable part of their particular ecosystems for hundreds of years. There is an increasing tendency to introduce exotic germplasm and/or to concentrate on a narrow range of supposedly more profitable breeds. As a result, indigenous breeds are threatened, even though they have been naturally selected for the local environments and are therefore best adapted. This paper describes the production systems in Africa and highlights the contribution of sheep and goats to subsistence farming systems and the general welfare of society. Problems preventing extensive utilisation and improvement of African animal genetic resources need to be identified. Genetic improvement programmes need to be developed. Breeds already endangered need to be conserved as a matter of urgency even if their economic value is not presently apparent. Concurrently, information should be compiled on biological performance and adaptive characteristics of these AGR (animal genetic resource) populations to aid the development of rational utilisation and conservation programmes.
Nécessité de caractériser et d'améliorer les races de petits ruminants africains indigènes
Résumé
Les demandes d'une population en expansion et les contraintes imposées par le développement économique compromettent la sécurité et la survie de nombreuses races indigènes africaines. Jusqu'à peu, ces races constituaient un élément stable des écosystèmes dans lesquels elles évoluent depuis des centaines d'années. Toutefois, on constate aujourd'hui une tendance à introduire du matériel génétique exotique et à investir dans un petit nombre de races censées être plus rentables. Les races indigènes sont de ce fait menacées, même si elles sont bien adaptées au milieu dans lequel elles évoluent, milieu dans lequel elles ont été soumises à la sélection naturelle. Cet article décrit les systèmes de production pratiqués en Afrique et fait ressortir le rôle des petits ruminants dans les systèmes de subsistance et le bien-être de la société. Les difficultés qui viennent contrarier l'utilisation extensive et l'amélioration des ressources génétiques animales africaines doivent être identifiées. Des programmes d'amélioration génétique doivent être mis en place. Les races déjà menacées doivent être protégées d'urgence, même si leur valeur économique n'est pas encore apparente. De même, des informations sur les performances biologiques et les caractéristiques d'adaptation de ces populations doivent être rassemblées afin de contribuer à l'élaboration de programmes rationnels d'utilisation et de conservation de ces ressources génétiques animales.
Indigenous sheep and goat breeds constitute over 95% of the small ruminant population of Africa. They are owned by the majority of smallholder rural farmers for whom this resource is critical for nutrition and income. They are also an important and secure form of investment. They provide the only practical means of using vast areas of natural grasslands in regions where crop production is impracticable. Low genetic potential is often quoted as a major constraint to meat and milk production in sub-Saharan Africa (SSA). Consequently, most livestock improvement programmes in the region have resorted to crossbreeding with imported exotic breeds or directly replacing the indigenous genotypes. This trend continues as the human population and the demand for animal products increases. As previously isolated communities intermingle, indigenous animal populations can interbreed. This, combined with increasing animal movements through trade, presents additional pressures on these populations. In some regions of Africa the effects of drought and famine, compounded by prolonged civil wars, have also taken their toll. Consequently, indigenous African breeds are at risk. However, sustainable livestock improvement cannot be guaranteed for some environments without the adaptive traits of these genetic resources. The rate of developments in biotechnology also suggests that it will soon be possible to identify and manipulate genes, including those which confer disease resistance and physiological adaptation to other environmental stresses. The potential global contribution of the genetic resources of indigenous small ruminants is tremendous. It would be tragic if unique genetic resources resulting from centuries of natural and artificial selection were lost. The rate of erosion of indigenous animal genetic resources therefore threatens prospects of providing the livelihood of present and future human generations. African policy makers and other development agencies need to recognize the role these resources play in today's production systems. Programmes should be set up to conserve and develop these resources in step with the evolving agricultural systems.
Table 1. Characteristics of agroecological zones of sub-Saharan Africa.
|
Agro-ecological zone |
Characteristics of the zone a |
Proportionate area % |
Proportionate human population % |
Proportionate TRLU population % |
Proportion of cattle population % |
Breed typec |
Predominant livestock production system |
|
Arid |
1.0-500 |
35 |
12 |
29.8 |
20.7 |
Indigenous |
Traditional nomadic, and transhumant based on communal grazing |
|
|
2.<75 days |
|
|
|
|
|
|
|
Semi-arid |
|
20 |
26 |
27.1 |
30.6 |
Indigenous, exotic (+) |
Nomadic, transhumant; Smallholder crop livestock |
|
|
1. 500-1000 |
|
|
|
|
|
|
|
|
2. (75-180 days) |
|
|
|
|
|
|
|
Subhumid |
1. 1000-1500 |
20 |
27 |
19.6 |
22.7 |
Indigenous, exotic (++) |
Smallholder crop-livestock; agropastoral |
|
|
2. 180-270 days) |
|
|
|
|
|
|
|
Humid |
1. >1500 |
20 |
20 |
6.1 |
6.1 |
Indigenous |
Small crop-livestock |
|
|
2. >270 days |
|
|
|
|
|
|
|
Highland |
(<20°C)b |
5 |
15 |
17.4 |
19.9 |
Indigenous, exotic (+++) |
Smallholder crop livestock; animal traction important |
|
Total |
- |
100 |
100 |
100 |
100 |
- |
- |
a) Line 1 = rainfall, mm; 2 = length of growing period. days.b) Highlands are defined as all those areas in the semi-arid, suhhumid and humid zones of SSA where, because of altitude, mean daily temperature during the growing periods is <20°C.
c) use of exotic ("improved") breeds: +++ = very important; ++ = moderately important; + = some importance; blank = not important.
d) TRLU = Tropical ruminant livestock unit
This paper discusses the role of indigenous small ruminants in African production systems and highlights the key attributes and functions which justify their conservation and improvement.
Africa is a continent of enormous environmental diversity. This is mainly due to variations in rainfall, altitude and soils. In general, there are close relationships between climate, land use and human population densities. These relationships are particularly strong in systems where there is little or no external input into the production system. Thus, the ecological zones, which are categorised mainly on climatic data, are quite closely linked with the production options and hence production systems (Table 1). In addition to the physical environment, characterising livestock production in these zones consists of assessing the key products and functions of livestock. Accordingly, the major livestock production systems in Africa (Table 1) are: pastoral range systems, usually found in the arid and semi-arid zones; agro-pastoralism in the semi-arid and subhumid zones; mixed crop-livestock systems found in the lowlands of subhumid zones and high rainfall areas of the highlands; and ranching range systems and introduced systems such as modern intensive dairy, beef, poultry and pig production which are increasingly common in pert-urban areas. Major characteristics of these systems have been described (e.g. Pratt and Gwynne, 1977; Jahnke et al, 1988).
ILCA (1987) has classified SSA into five principal agroecological zones. These are the arid, semi-arid, subhumid, humid and highland zones. The arid zone covers over a third of the region. The semi-arid, subhumid and humid zones each occupy about a fifth while the highland areas make up only 5% (Winrock International, 1992) of the total land area. East Africa contains 70% of the highlands and central Africa has about 75% of the humid zone (ILCA, 1987). On the other hand, arid, semi-arid and subhumid zones are important in all subregions of SSA except Central Africa, where the arid and semi-arid zones are marginal.
The close association between agroecological zones and production systems is apparent from Table 1. Both pastoral and ranching systems are largely based on range, primarily utilising natural vegetation. However, the major outputs and their importance differ between these systems. Pure pastoralism is practised in the arid to very arid ecological zones, defined as those with an annual rainfall of less than 400 mm. The major product from these systems is milk; the major livestock role is for subsistence and cultural or social functions (Jahnke, 1982). The major functions of livestock in the ranching systems are meat and cash incomes. The contribution of livestock in a mixed crop-livestock system is measured in terms of the increase in overall farm productivity attributable to the presence of livestock.
The population of sheep in SSA is estimated at 127 million head, while that of goats is estimated at 147 million (Winrock International, 1992). The arid and semi-arid zones together hold the majority of sheep (57%) and goat (64%) populations of sub-Saharan Africa. However, the arid holds 11% more sheep and 12% more goats than the semi-arid, which contains 23 and 26% of the sheep and goats, respectively. More sheep are found in the highland zone than in the humid zone (21 and 8% respectively), but the humid and the highland zones account for about equal proportions of the population of goats (9 and 10% respectively). The population of sheep and goats in the subhumid zone are 14 and 17%, respectively. Thus, the arid and semi-arid zones account for the majority of small ruminants in the region. However, these species are an important livestock component in all agroecological zones. In addition, small ruminants are found in all production systems ranging from pastoral and agropastoral systems to ranching range systems to smallholder mixed crop-livestock systems.
Sheep and goats are highly adaptable to a broad range of environments. They can utilise a wide variety of plant species and are thus complementary to cattle and camels. They generally do not compete directly with these species for feed. For example, a mixture of animal species on semi-arid rangelands makes it possible to change the stocking rate from 26 ha per tropical ruminant livestock unit (TRLU) (250 kg liveweight equivalent) for cattle alone to 13 ha per TRLU when cattle and goats are reared together and to 10 ha per TRLU when camels are included (Schwartz, 1983). It is the complementarily of the ruminant species that maintains the high animal biomass that characterises pastoral production systems. Goats are more effective at grazing selectively than any other domestic livestock species (Winrock International, 1976) and they utilise poor quality forage and browse better than sheep. Goats also walk longer distances in search of food than do other domestic livestock (Wilson, 1991).
Due to their short generation lengths and high reproductive rates, small ruminants have a high production efficiency (Winrock International, 1976). In addition, the energetic efficiency of milk production may be higher in dairy goats than for other dairy animals (Winrock, 1976). Certain breeds of sheep (e.g. Djallonké and goat (e.g. West African Dwarf) are thought to be tolerant of trypanosomiasis and other diseases, allowing them to be grazed on land not available to other domestic livestock.
Small ruminants are useful to humans during periods of cyclical and unpredictable food shortages. They also help balance the energy and protein supply during normal variations between seasons and years. The small size and early maturity of sheep and goats give them several distinct economic advantages in smallholder situations, such as: they can efficiently utilise marginal and small plots of land; the risk on investment is reduced by smaller individual size, allowing more production units per unit of investment; and there is a faster turnover of capital because they are sexually mature early and are younger at slaughter. Smaller carcasses are also easier to market and can be consumed in a short period of time. This is important as most rural areas lack proper storage facilities. Their strong flocking instinct makes herding by younger and older members of the family possible, allowing labour to be used more efficiently.
Small ruminants produce lower absolute quantities of milk than cattle. However, when their body weight is taken into account, their milk yield is higher than other species with the possible exception of camels (Wilson, 1991). During difficult periods of the year, these minor levels of output become significant (Coppock et al, 1982). It has been estimated that up to 40 years may be needed for cattle to attain the population and production levels existing prior to a drought (Wilson, 1991). Because of their shorter generation length and higher reproductive rate, small ruminants have a much shorter recovery period. For example, following a severe drought, goats conceive as soon as there is sufficient moisture for leaves and browse plants to grow. They kid five months later and consequently produce milk for human consumption at a very early phase of the recovery cycle (Wilson, 1991).
Although regional and breed variations exist, small ruminants appear to withstand drought better than cattle (Campbell, 1978). The droughts of the early 1980s which affected Ethiopia and the Sahel, including Sudan, resulted in cattle losses of 80% or more. Small ruminant losses did not exceed 50% (Wilson, 1991). Shafie (1992) has summarised the physical and physiological characteristics which enable sheep and goats to survive in arid and saline environments. They include: body conformation (slim trunks and slender limbs) which provide a large proportional surface area, helping excess body heat dissipate through non-evaporative cooling; and a respiratory system with a larger proportion of dead space to respiratory space, a structure which facilitates heat dissipation via respiratory water vaporisation without the need for severe panting. Due to their adaptation to the environment (including feeding behaviour), small ruminants, particularly goats, are often the last to be affected by catastrophes. This causes them to be blamed for desertification.
Table 2 Sub-Saharan Africa's estimated livestock and meat and milk output by agroecological zones (1988).
|
Species and agroecological zone |
Meat output |
Milk output |
|||||
|
Inventorya (millions) |
Off take (%) |
Carcass wt (kg) |
Quantity ('000 tonnes) |
Inventoryb (millions) |
Lactation (kg) |
Quantity ('000 tonnes) |
|
|
Cattle (total) |
162.5 |
10.4 |
137 |
2315 |
25 |
330 |
8200 |
|
Arid/semi-arid |
84 |
10 |
140 |
1176 |
13 |
250 |
3300 |
|
Subhumid/humid |
46 |
10 |
130 |
598 |
7 |
200 |
1400 |
|
Highlands |
32 |
12 |
140 |
538 |
5 |
700 |
3500 |
|
Sheep and goats |
269 |
25 |
14 |
942 |
|
|
2128c |
|
Sub total (red meat) |
|
|
|
3257 |
|
|
|
|
Poultry |
630 |
110 |
1.3 |
900 |
|
|
|
|
Pigs |
11 |
79 |
40 |
348 |
|
|
|
|
Sub total (white meat) |
|
|
|
1248 |
|
|
|
|
Total |
|
|
|
4505 |
|
|
10,328 |
Source: Adapted from Winrock (1992).
a) Total population.
b) Milked population only.
c) Calculated from 1985 (FAO, 1987) country statistics.
Small ruminants as source of food
Human diets will not contain necessary amounts and kinds of amino acids unless they include protein from either animal products or an unusually well designed combination of foods from plants (FAO, 1983).
It is difficult to determine accurately the contribution of small ruminants to human food supply and general welfare. Available statistics are misleading because much of the production from these species does not enter formal trade channels and is therefore not reported. Estimates indicate that ruminants contribute 80% of the total food production from livestock in tropical Africa (Jahnke, 1982). Of this, small ruminants account for about 22%. It is estimated that ruminants supply over 3.2 million tonnes of meat per year, representing over 72% of total meat production (Table 2). Small ruminant meat accounts for about 30% of the total red meat production and over 20% of the total meat output of SSA. Small ruminants account for about 21% of the total milk produced in SSA. This is about 26% of the milk output from cattle in the region (Table 2). The figures on meat production have been calculated from carcass weights which, in turn, were estimated from assumed dressing percentages. In the African context, and indeed in most developing countries, the conventional concept of dressing percentage is inappropriate when almost all parts of the animal are consumed. Thus, actual meat outputs from these species in traditional production systems are expected to be higher than estimates in Table 2. Most importantly, production from these species makes a valuable contribution to food resources in areas where it is most needed.
Small ruminants as producers of manure
Few farmers have access to commercial fertilizers. Manure and urine from domestic animals are therefore essential components for maintaining agricultural production. However, only limited quantitative data are available on the contribution of manure in traditional production systems. While some data are available on the contribution of cattle to manure production (e.g. Rege and Agyemang, 1992), data on the contribution of small ruminants is scanty.
Asset and security functions of small ruminants
One of the reasons usually given for low live animal offtake from traditional herds is the holding of livestock as a status symbol or sign of wealth. Livestock owners in rural areas do not usually have access to banking facilities and have come to rely on investment in their stock. While investment in livestock does carry its own risks, it provides security against crop failure and currency fluctuations. An analysis of income accruing from crops and livestock in a mixed farming situation was carried out in Abet, northern Nigeria. It revealed that, among farm items sold, livestock and livestock products accounted for 56% in value terms (Ingawa, 1986). Crop sales were limited to certain seasons, but the sale of livestock and milk was less season dependent. It therefore represents a dependable asset for emergencies. In general, livestock contribute to the stability of farm income because they can be bought following good crop performance and sold following crop failures. Thus, livestock helps to cushion farm enterprises against unstable commodity prices during unfavourable years. Livestock also serves as a "currency" in which social obligations are expressed.
Small ruminants facilitate utilisation of marginal lands
About 13-16 million km², or nearly half of the continent south of the Sahara, is desert or arid grassland and savanna. Crop production is a high risk enterprise (Brown, 1971). Nearly all livestock in these zones are indigenous African breeds raised under traditional nomadic and transhumant pastoral systems based upon communal grazing. They are well adapted to the characteristically sharp annual and seasonal variations in rainfall, requiring mobility in search of forage. These land use systems efficiently utilise available vegetative resources and provide a reliable source of food for the population (Cossins, 1983). Frequent reference to low land productivity of the pastoral range livestock production systems ignores the fact that livestock farming is the only way to support any human life at all in much of this zone. Wilson and Light (1986) have reported that as many as 95% of agropastoral families in Mali own goats and that the average flock size per family is over 30 head.
Overall contribution of small ruminants to national economies
A rough estimate of the importance of the livestock sector to the national economy is its contribution to the Gross Domestic Product (GDP). The share of agriculture to the GDP is important in Africa, but varies from 2.2. and 2.3% for Gabon and Côte d'Ivoire respectively, to 35.7% for Zimbabwe, 38.7% for Chad and 81.6 and 86.3%, respectively for Somalia and Mauritania. The average for the continent is 17.4% (Jahnke et al, 1988). The share of livestock in agricultural GDP has been estimated at 25% but this increases to 35 % when traction and manure are considered (Winrock International, 1992). However, these averages hide great differences between countries, ecological zones and subregions. For example, the share of livestock in agricultural GDP's ranges from 5% for Ghana and Côte d'Ivoire to 82,84 and 88% for Namibia, Mauritania and Botswana, respectively (Winrock International, 1992). On the basis of dollar values used by Winrock International (1992) for meat and milk, monetary contributions of small ruminants to GDP were estimated for 1988. Meat output contributed about $1286 million while milk output contributed about $1162 million.
In general, livestock products do not contribute much to direct foreign currency earnings in African countries. The exceptions include countries like Botswana, Swaziland, and Zimbabwe which export beef and mutton and Kenya which exports meat and indigenous animal germplasm (both live animals and semen). Several countries (e.g. Ethiopia) also export hides and skins. However, products from small ruminants offer local alternatives to imported products thereby saving foreign currency. The highest per capita consumption of animal products outside pastoral areas occurs in urban areas. If there were no local supply of these products, the demand would have to be met through importation. Even where small ruminants do not actually produce exportable products, they provide for the local demand, allowing the export of prime beef and mutton from limited high-input systems. In this way they contribute indirectly to export earnings. They also contribute indirectly to the employment of urban labour in the packing industry.
The majority of sheep and goats in tropical Africa are "indigenous" types, although both species were originally domesticated in Asia (Epstein, 1971). In the last 150 years or so exotic breeds have been imposed, mainly for modern commercial operations (Wilson, 1991). The Republic of South Africa has been in the forefront of this movement. There are large populations of Merino sheep in Kenya and Zimbabwe, and Karakul sheep in Namibia. Merino are also important in the smallholder sector of Lesotho, as are Angora goats (Wilson, 1991). The latter are also gaining prominence under commercial systems in Kenya. Karakuls are present in Angola, Botswana and Rwanda, but in smaller numbers. A composite breed, the Dorper, was bred in the Republic of South Africa from the Dorset Horn and Blackhead Persian. It is rapidly gaining ground for meat production under local conditions, notably in Zimbabwe, Kenya and, more recently, Botswana. Other countries have also imported exotic breeds but on a lesser scale than in the southern African region and Kenya.
In general, pressures of exotic breeds on indigenous types is much less for small ruminants than for cattle, where the contribution of AI to crossbreeding and breed substitution has been considerable. However, as is the case with indigenous cattle, breeds are not distinct from one another. There are hardly any indigenous small ruminant breeds which have been adequately characterised. Even so, it is widely recognised that because these genetic resources have evolved under the stresses of the African environment, they are well adapted to the local conditions.
The broad genetic variability of African small ruminant breeds enables them to survive under stressful environmental conditions, including high disease incidence, poor nutrition and high temperatures. Environmental pressure also maintains a wide range of genotypes, each adapted to a specific set of circumstances. This is clearly the species' genetic response to risk. Under on-station management, indigenous African sheep and goat breeds have shown good growth and reproduction performances, indicating their potential. This shows that they would respond to improvements in management, particularly nutrition and disease control. This should be accompanied by selecting for improved performance. However, African livestock producers are not yet in a position to organise breed improvement programmes. Governments should therefore take responsibility for the development and implementation of selection schemes.
Studies indicate that the performance of small ruminants could be improved through management. Additionally, estimates of genetic parameters point to considerable genetic variation within indigenous populations. This indicates the potential for genetic improvement through selection.
There has been a tendency to over-emphasise the low productivity of indigenous breeds without due consideration of some important characteristics of these breeds. When the small size of these breeds and the harsh environmental conditions under which they are raised are taken into account, their productivity is impressive. Comparative studies of indigenous and exotic breeds to determine their feed utilisation efficiency have not been conclusive. However, it is known that breeds with high maintenance requirements tend to lose the most weight and have the highest mortality rates under stress conditions such as drought (Frisch, 1984). Most breed comparison studies have concentrated on quantifying performance (e.g. live weights and milk production) but not inputs. Indeed, the high-performing temperate breeds cannot survive under traditional management in most African environments. Although the performance of indigenous breeds under improved management has not been adequately assessed, there are indications that they respond to improved husbandry. For example, Kolff and Wilson (1985) have reported that indigenous small ruminants were able to double their daily weight gain rate with only minimal improvements in nutrition and management. The ability to survive under adverse environmental conditions with low inputs makes indigenous breeds a low-risk choice. The low-risk factor of resistant breeds is important where market prices are unstable or where the probability of death from environmental stress is high (Frisch, 1984). In some cases "low productivity" is an adaptive mechanism. For example, delayed age at first parturition and extended parturition intervals in semi-arid environments are mechanisms for coping with seasonal and often unreliable feed availability. In such environments some flock owners deliberately delay first breeding (Wilson et al, 1984). Poor nutrition increases the animals' susceptibility to diseases. Animals that have low maintenance requirements and the ability to make efficient use of poor quality forages are therefore at an advantage. There is a need for comparative evaluation of indigenous and exotic breeds in African environments, taking input costs and output prices into account.
Most imported (temperate) breeds are raised on high potential agricultural land where crop farming is practised. The critical role of indigenous breeds is in providing the only means of using areas where other forms of agriculture are not practical. It may not be possible to improve some of these environments, especially in the arid zone, to accommodate exotic breeds. However, the strategy will most probably be some kind of crossbreeding to take advantage of breed complementarily and/or upgrading to allow gradual improvement in husbandry. Additionally, recent developments in biotechnology indicate that direct transfer of genes may become a routine method for germplasm improvement. Thus there is need to keep a reservoir of these exceptional genes. Indigenous breeds are crucially important today and will continue to be valuable in the future.
Several expert panel meetings have addressed the issue of conservation of indigenous breeds, at both global and regional levels. These meetings have involved, among others, the Food and Agriculture Organization (FAO) of the United Nations (UN), the Organization of African Unity (OAU) through its Inter-African Bureau for Animal Resources (IBAR), UN Environmental Programme (UNEP), National Agricultural Research Systems (NARS) and other International Agricultural Research Centres (IARCs), including ILCA. However, efforts in support of Animal Genetic Resources (AGRs) have mainly remained at the stage of studies to identify priorities. Recognising the need to go beyond studying options and actually to implement them, in 1991 ILCA launched a research project to characterise indigenous African AGRs. ILCA's research initiative is aimed at documenting population sizes, biological performance and adaptive or other special characteristics of these AGRs. This information can then be used to develop rational utilisation and conservation programmes. In February 1992, ILCA organised a research planning workshop to work out methodologies and outline the implementation process. The workshop was attended by NARS scientists and AGR experts from FAO, several IARCs and other institutions outside Africa. Details of the AGR programme for Africa proposed by the FAO were presented. It immediately became clear that, given the scale of the undertaking and the common objectives of ILCA and FAO's proposed programmes a collaborative programme would be more effective. Subsequently, joint proposals have been prepared and funding is currently being sought.
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