PART ONE
INTRODUCTION

DESCENT AND DOMESTICATION OF GOATS AND SHEEP

Goats and sheep both belong to the tribe Caprini of the family Bovidae in the sub-order Ruminantia of the order Artiodactyla (Zeuner, 1963; Epstein, 1971; Corbet, 1978; Corbet & Hill, 1980; Ryder, 1984). They are typical cloven-hoofed ruminants of relatively small size.

The tribe Caprini is comprised of five genera. Two of these genera, Capra and Hemitragus, are true goats; one genus, Ovis, is the sheep; and there are two genera -- Ammotragus and Pseudois -- of goat-like sheep or sheep-like goats.

The Barbary sheep or aoudad, Ammotragus lervia (Figure 1), is confined to the Sahara and the bharal or blue sheep, Pseudois nayaur, to the Himalayas: neither of these have been domesticated and neither will hybridize with true sheep of the genus Ovis. Fertile offspring by male Barbary sheep out of female domestic goats are known, however.

According to latest taxonomic opinion the two genera of true goats are divided into three species of Hemitragus or tahrs, and six of Capra. All the tahrs have the same chromosome number (2n=48). Most of the Capra species are interfertile although for some pairs no crosses are recorded: all the species examined (bezoar, ibex and markhor) have the same number of chromosomes (2n=60).

Figure 1 A female Barbary sheep Ammotragus lervia at Khartoum zoo

Hemitragus jayakari: Arabian tahr, found now only in Oman and in danger of extinction;

Hemitragus jemlahicus: Himalaya tahr;

Hemitragus hylocrius: Nilgiri tahr of southern India;

Capra aegagrus: Bezoar or wild goat with five sub-species: the domestic variant is classed as Capra hircus;

Capra ibex: Ibex, with four sub-species in the Alps; in central Asia; in the Near East, Egypt and Sudan (C.i.nubian) (Figure 2); and in the Simen Mountains of Ethiopia, this last being C.i.walie;

Capra caucasica: West Causasian tur or kuban which until recently was considered as a sub-species of the ibex named C.i.severtzovi;

Capra cylindriocornis: East Caucasian tur which was earlier called C.caucasica;

Capra pyrenaica: Spanish ibex or wild goat with two sub-species;

Capra falconeri: Markhonr of Afghanistan and Pakistan with six or seven sub-species.

The nomenclature of the genus Ovis is confused bur latest opinion tends to favour six wild species.

Ovis orientalis: Mouflon, with one sub-species in Asia (O.o.laristanica) and one in Europe (O.o.musimon);

Ovis ammon: Argal, with nine sub- species;

Ovis vignei: Urial, with thirteen sub- species. Ovis orientalis is some-times considered synonymous with O.vignei;

Figure 2 Nubian ibex Capra ibex nuniana in captivity at Khartoum zoo

Ovis canadensis: Bighorn, with eight sub-species in Canada and the United States of America;

Ovis nivicola: Snow sheep of Siberia with three sub-species;

Ovis dalli: Thinhorn of Alaska also with three sub-species;

All these "species" of Ovis are fully interfertile and might therefore be considered to be monotypic. To distinguish them from the wild types, all domesticated sheep are now classed as Ovis aries. The mouflon has the same number of chromosomes as the domestic sheep (2n=54) while the urial (2n=58) and the argal (2n=56) differ.

Of the six species of Capra, it is most likely that only C.aegagrus blood is present in the modern domestic goat although a slim possibility still remains that the markhor, C.falconeri, may have been involved in the ancestry of some Indian breeds.

The bighorn, 0.canadensis, and the thinhorn, 0.dalli, are excluded, on geographical considerations alone, from the ancestry of domestic sheep. Some authorities, on the grounds of chromosome number, consider the mouflon to be the sole ancestor of the domestic sheep. Both the argal and the urial, however, freely interbreed with, and produce fully fertile offspring from, the domestic sheep and therefore cannot be excluded from its ancestry.

Domestic goats and sheep, because of the divergence in chromosome numbers, do not usually interbreed (Gray, 1972). Experimental chimaera are known (Fehilly, Willadsen & Tucker, 1984; Meinecke-Tillman & Meinecke, 1984) and one of these, back-crossed to a ram, is reported to have produced twin offspring (Bunch, Foote & Spillet, 1976).

The most simple and effective visual way of separating goats from sheep is the carriage of the tail -- in all domestic forms, goats' tails are erect while those of sheep are pendent. There are, however, a considerable number of additional morphological differences between the two species. Goats have beard and caudal (i.e. at the tail) scent glands in the male. Sheep have suborbital (under the eye) tear glands and lachrymal (tear) pits in the skull and also possess foot glands: goats may, however, have glands in the forefeet. Both species differ from cattle in normally having only two nipples instead of four.

Goats were almost certainly the first ruminants to be domesticated and were possibly only the second species to be taken into the human fold after the dog. South-west Asia (Iran and Iraq) is the most likely origin of the domestic species, the bezoar, C.aegagrus, being present there. Domestication occurred gradually over a period centred about 9000 years Before Present (Mason, 1984). Domestication of sheep possibly followed closely upon that of the goat and took place in the same area. Both goats and sheep appeared in tomb and cave paintings in Egypt by about 7000 years BP. Goats moved into sub-Saharan Africa by at least 5500 years BP and a dwarf type has been recorded from that period near Khartoum in Sudan. Sheep probably entered Africa with cattle, at some time in the period 6000-5000 BP, possibly slightly later than goats.

SMALL RUMINANT PRODUCTION SYSTEMS IN TROPICAL AFRICA

Tropical Africa contains one-third of all the world's goats and one-sixth of its sheep. On average there is one goat or sheep on every 10 ha of tropical Africa and there are 1.1 head of goats and sheep per person employed in the agricultural sector. Goats and sheep are equivalent, in weight terms, to about 17 per cent of the total domestic ruminant biomass (DRB) of tropical Africa.

Total meat production from African goats and sheep combined is estimated (FAO, 1985) at 1.15 million tonnes, equivalent to about 16 per cent of total world output from these species. Milk from small ruminants is 1.99 million tonnes, about 14 per cent of world production. Small ruminant skins from Africa, estimated at 258 000 tonnes, represent about 16 per cent of world production, the proportion from goats (25 per cent) being much greater than that from sheep. African wool production, of about 228 000 tonnes, is equivalent to less than 8 per cent of world output and most of this wool is produced in South Africa and Africa north of the Sahara. Goats in tropical Africa are much more important than sheep as milk producers and she-goats (does) are estimated to produce about three times as much milk in total as are ewes.

DISTRIBUTION AND IMPORTANCE OF GOATS AND SHEEP

The major criteria adopted for assessing the distribution and importance of goats and sheep are: the ratios of goats to sheep; the density per unit area of both species combined; the ratio of goats and sheep to the human population involved in agricultural activities; and the contribution of goats and sheep to the total domestic ruminant biomass.

Ratios of goats to sheep

In tropical Africa as a whole, goats outnumber sheep in the ratio 1.16:1.00. There does not appear to be any overall pattern in the relative importance of goats and sheep related to the major ecological zones or to the major production systems, at least at the country level (Figure 3).

Goats are dominant and exceed sheep by a ratio of 4:1 in widely disparate countries. The highest ratios of more than 11:1 are found in the Central African Republic and in Zambia. Both countries have low densities of small ruminants, low ratios to the human population and a low contribution of small ruminants to total ruminant biomass. Swaziland has a ratio of goats to sheep exceeding 8:1. The ratio of goats to sheep in Botswana approaches 5:1, this country in general being much drier than the others where high ratios are found and also having a largely pastoral vocation.

Countries in which goats remain dominant over sheep in ratios varying from 2:1 to 4:1 also appear to have few factors in common, either in terms of agro-ecology or of principal production systems. They include the mainly pastoral Niger (2.1:1.0) and neighbouring Nigeria (2.0:1.0). They also include the largely agricultural countries of Zaire (3.8:1.0) and Mozambique (3.1:1.0) as well as some countries with mixed agricultural-livestock economies such as Angola (3.8:1), Zimbabwe (3.4:1.0) and Madagascar (2.5:1.0). The two small central African highland republics of Rwanda (2.9:1.0) and Burundi (2.2:1.0) also fall within this group.

Figure 3 Ratios of goats to sheep in tropical Africa

Sheep assume more importance but are still fewer in number than goats in the major East African countries and in some of the Gulf of Guinea states in West Africa. Somalia has a ratio of goats to sheep of 1.6:1.0, Djibouti of 1.3:1.0, Kenya of 1.2:1.0, Uganda of 1.7:1.0 and Tanzania of 1.6:1.0. In West Africa the ratio varies from 1.3:1.0 in Burkina Faso to about parity in Guinea, Côte d'lvoire and Ghana.

Goats are less numerous than sheep across much of the Sahel. In Senegal there is only one goat for every two sheep and in Mauritania there are two goats for three sheep. In Sudan and Ethiopia (and also in Gabon and Lesotho) the proportion of goats to sheep is about 0.7:1.0 while in Chad it is about 0.9:1.0. Sheep are more important than goats in Namibia, largely because of the pelt industry, and outnumber them in the ratio of 1.0:0.4.

Density

Small ruminants achieve their highest densities in two distinct areas (Figure 4). More than 35 goats and sheep per square kilometre are found in the Horn of Africa in Somalia and Djibouti where people are traditionally pastoralists. Very high densities are also found in Ethiopia where much of the northern, eastern and southern lowlands also have a pastoral vocation. An additional factor in the high densities in Ethiopia is that the highlands have heavy concentrations of people, the case being similar in the small central African highland republics of Burundi and Rwanda. On a finer scale, the eastern Zaire province of Kivu would also show high densities. Large numbers of small ruminants are also found in Nigeria due to the same combination of a pastoral vocation (in the north) and large numbers of people (in the centre and south) as in Ethiopia.

Figure 4 Densities of small ruminants per unit area in tropical Africa

Medium densities (18-35 head/km²) of small ruminants are found in countries where there is relatively heavy human population pressure and where they can be integrated with crop farming in mixed smallholder systems. Examples are Togo and Benin in West Africa (countries which are less humid than their immediate neighbours in the Gulf of Guinea) and Uganda and Kenya in East Africa (although Kenya is also largely pastoral in the north and north-east).

Lower densities (7-18 head/km²) are found in all the West African Sahel countries and in Sudan. On a regional basis, densities would probably be in the highest class in the southern areas of this group of countries but large tracts of desert in the north are sparsely populated. Low to extremely low densities are also found in the coastal Gulf of Guinea states mainly because the people are principally agriculturalists but possibly also because of tsetse fly infestation and other humid-associated disease problems.

Very low densities (< 7 goats and sheep/km²) are found from Chad (which is very sparsely populated), through central Africa and into the southern states of Botswana and Zimbabwe. With the exception of the two last named, agriculture is the main preoccupation of the human population and trypanosomiasis is also a problem. Zimbabwe has many more cattle than small ruminants, mainly for socio-cultural reasons, and Botswana, like Chad, is very sparsely populated. Madagascar also falls into the lowest density class.

There are three major exceptions to the general rules governing density of small ruminants. Tanzania has a low human population in relation to its resource potential. Namibia is very thinly populated and has developed an important industry based on pelt production from Karakul sheep. Lesotho is in the highest density class for reasons similar to Namibia in that it has developed specialist production of mohair from Angora goats and fine wool from Merino sheep.

Numbers of goats and sheep per person

Highest ratios of goats and sheep to humans (> 2.5:1.0) are found in the principally pastoral countries (Figure 5 ). These include, again, Somalia and Djibouti but also Mauritania. Namibia has by far the highest ratio of small ruminants to humans (13.5:1.0), almost twice as great as in Mauritania (7.6) and Somalia (7.4).

Figure 5 Relationships of total numbers of goats and sheep to the numbers of people in tropical Africa

Intermediate ratios (1.3-2.5 head per person) are found in countries where large segments of the population in the drier areas are pastoralists. These include Mali, Niger and Sudan in the north and Botswana in the south. Small, mountainous Lesotho also appears in this intermediate class because, whilst having the highest density (78.9 head/km²) of goats and sheep of all African countries, it also has a large human population in relation to its area.

Low (0.7-1.3 head/person) and very low (< 0.7 head/person) ratios prevail in the remainder of Africa. In Ethiopia the highland, mainly agricultural, areas have a population of farmers which greatly outnumbers the pastoral peoples of the lowlands and the situation is similar in Kenya. Togo and Benin, as well as Burundi and Rwanda, which are in the high density classes for small ruminants, also have large human populations, this leading to low numbers of goats and sheep per person. Large numbers of people in the south and centre of Nigeria also impose a low ratio in this country.

Most of the central belt of the continent, from the Atlantic Ocean to the Indian, has very low ratios of small ruminants to people in addition to low densities.

Small ruminants as a proportion of all domestic ruminants

The contribution of goats and sheep to total DRB (Figure 6) has been calculated on the basis of the mean population weight (MPW) of each species. The MPW is the average weight of each animal in the herd or flock and is obtained from weights at specific ages and for different sexes. Although there are obviously some regional differences, MPWs have been standardized at 307 kg for camels, 206 kg for cattle, 30 kg for sheep and 18 kg for goats.

The distribution of the highest proportions (> 25 per cent) of small ruminants in DRB is rather surprising at first sight as it coincides mainly with the humid Gulf of Guinea and central Atlantic coast countries. The reasons for this might be related to the better tolerance, compared to cattle, of goats and sheep to trypanosomiasis. It is also possible that the mainly agricultural peoples of these areas can handle small ruminants more easily than they can cattle. It should, however, be borne in mind that overall animal numbers in these countries are few. Mauritania.is the only pastoral country where goats and sheep fall into the highest proportional class although Namibia with a "modern" pastoral economy also has a high relative biomass of small ruminants.

Figure 6 The contribution of small ruminants to total domestic ruminant biomass in tropical Africa

Small ruminants are of considerable (15-25 per cent of DRB) importance in the total livestock mix in most of the remaining pastoral or principally pastoral countries. Of the two such countries that are not in this class, Sudan does have 14 per cent of DRB as goats and sheep. Small, intensively cultivated countries with high goat and sheep densities also fall into this grouping.

Lower proportional contributions (8-15 per cent) to total livestock are shown in Ethiopia (where heavy draught oxen are extremely important) and in Kenya and Uganda where the "cattle complex" tribes are predominant.

In most of the southern African states and in Madagascar, small ruminants contribute very little (< 8 per cent) to livestock biomass and, taken in combination with the two previous factors, can be seen to be relatively as well as absolutely unimportant in this region.

PRODUCTION SYSTEMS

Ecological zones

Livestock production systems are influenced by the annual rainfall and its effect on the main vegetational characteristics.

The arid zone, associated with pastoral production, includes all areas receiving less than 600 mm of rainfall per year. The zone has two major sub-zones. The first has less than 200 mm of rain per year and no agriculture at all is possible outside a few oases or other irrigable areas. Where rainfall is less than 100 mm per year, the natural vegetation is of the Saharan type. The second sub-zone has rainfall of 200-600 mm per year and is often called the Sahel zone in northern and western Africa. Some agriculture is possible but crop failures are frequent and yields are generally low as the coefficient of variation of rainfall is in the range 25-35 per cent.

In the semi-arid zone, rainfall is between 600 and 1000 mm per year. Livestock raising is usually intimately associated with crop production. Vegetation is of the south-Sahelian or north-Sudanian type in northern and western Africa. In eastern and southern Africa the lightly forested 'miombo' areas are part of this ecological zone. Rainfed millets {Pennisetum, Eleusine, Digitaria, etc.) are the principal cereal crops but these are replaced by sorghum and maize where rainfall is better and where year to year variation is less. Some cash crops such as cotton and groundnuts may be grown in the more favoured areas. The coefficient of rainfall variation is generally in the region of 20-25 per cent.

The sub-humid zone is a high potential area with rainfall of more than 1000 mm per year. The main vegetation is of the Sudanian and south-Sudanian types, large trees often being broad-leaved and deciduous. Sorghum and maize are the principal cereal crops, a number of cash crops are grown and some tuberous root crops appear as food staples towards the boundary of the humid zone.

The humid zone is characterized by an annual rainfall in excess of 1500 mm. Although a "dry" season may sometimes be recognised, rainfall usually exceeds evapotranspiration throughout the year except for a very short period. This zone is essentially found in coastal West Africa and some parts of central and central-west Africa. Livestock production in the humid zone is currently not very important as an economic activity but the potential is considered to be high providing that the problems of tsetse flies and trypanosomiasis can be overcome.

Highland areas are those with an altitude above sea-level of more than 1500 m. Rainfall is not taken into account in defining this zone. The major crops are cereals (tef Eragrostis tef, barley and wheat in Ethiopia, maize and sorghum elsewhere), pulses, and bananas or plantains. Livestock production is generally an important secondary activity on the small farms that are typical of this zone. In some areas extensive or intensive commercial, purely livestock operations have developed.

Large areas of seasonally flooded land or areas capable of being permanently irrigated can be considered as a quite separate ecological zone. On account of the possibilities of out-of-season conservation of fodder and the quantities of crop and agro-industrial by-products potentially available, these are important livestock producing areas.

Livestock production systems

In Africa, it is possible to distinguish two major types of production systems. These are the traditional systems and the modern ones. Some major characteristics of each group of systems are provided in Table 1. The two groups differ essentially in their use of the main factors of production, with traditional systems using mainly land and labour while modern systems also have large capital requirements and generally a lesser requirement for one or other of the remaining factors.

Two principal criteria serve to define traditional systems. The first is the degree of dependence of the household or the production unit on livestock or livestock products either for household income or for food supply. The second is the type of agriculture practised in association with livestock production. The distance and duration of movement (transhumance, migration) might also be used to define systems and it is recognised that this is an important aspect of management within a system. It is considered to be a secondary one, however, subordinate to the two major ones just discussed.

Rather arbitrary limits have been set to define the systems. A system in which more than 50 per cent of gross household revenue or more than 20 per cent of total household food energy derives directly from livestock is considered to be a pastoral one (Wilson, de Leeuw & de Haan, 1983). The term "derived from livestock" in relation to revenue would also include the value of any transport (donkeys carrying firewood, camels carrying salt, etc.) plus sales or exchange of manure plus income from any other minor functions.

An agro-pastoral system is one in which between 10 and 50 per cent of household revenue derives from livestock or livestock products. A third, agricultural, system be one in which revenue from livestock amounts to less than 10 per cent of the total. In the modern African context, one must not omit the urban or peri-urban systems. These last are assuming increasing importance in many countries and one may cite the cases of Nouakchott and Djibouti for camel dairies, Khartoum and Mogadishu for goat production, and Ethiopia and many west African regional centres where donkeys provide transport of domestic fuel and building materials.

Table 1 A classification of small ruminant production types and systems in tropical Africa

Within the pastoral system, three major sub-systems can be identified. The first is a pure system in which little or no agriculture is practised. Examples are the camel cultures of the northern Sahel and (at least until the 1960s) the Masai system in eastern Africa. In the pure system, mobility is often high, and long distances might be covered in search of grazing and water. The second pastoral sub-system is found in the semi-arid regions and is one in which livestock production is associated with dryland or rainfed agriculture. Examples of this system are many of the Fulani groups of West Africa, most Baqqara in Sudan, and the Wagogo in Tanzania. In the livestock-rainfed agriculture system, cattle, sheep and goats are often of equal importance and donkeys provide many of the needs of transport. Draught animal power (oxen, donkeys and occasionally horses) and the use of, or exchange of, manure are important elements of this major sub-system. The third pastoral sub-system is associated with oases or with large irrigated areas. Some Touareg groups, the Macina Fulani of the Niger inundation zone in Mali, a number of Nilotic tribes in southern Sudan and areas in Zambia and Mozambique provide examples of this sub-system.

In the agro-pastoral system, livestock are usually sedentary or, if movement is part of the management practice, it is generally restricted to short distances. The three major sub-systems here are those associated with rainfed subsistence agriculture, rainfed cash cropping, and large-scale permanent irrigation of cash crops.

Some examples from West Africa of these different production systems are provided in Table 2 (Wilson, de Leeuw & de Haan, 1983) and a more detailed analysis of Systems in the sub-humid zone of Côte d'Ivoire is shown in Table 3 (adapted from von Bassewitz, 1983).

Table 2 Characteristics of small ruminant production Systems in West Africa

Note: 1) TLU is a Tropical Livestock Unit of 250 kg live weight equivalent.

Without being able to provide precise figures, it is probable that in the arid zone 70 per cent of small ruminants are found in pure pastoral Systems and 30 per cent in agro-pastoral Systems. In the semi-arid zones the figures are reversed with 70 per cent of small ruminants in the agro-pastoral Systems. In the more humid areas, virtually ail small ruminants are in the agro-pastoral System with a small percentage being found in the agricultural and urban Systems.

The relative importance of the main domestic species varies across Systems. Camels are important only in the driest pastoral areas. Cattle are probably the main species in ail Systems when these are considered as a whole. In agro-pastoral Systems, goats are generaily more numerous than sheep although only recently is this fact being recognised by the official statistical services.

Table 3 Small ruminant production systems in Cote d'lvoire

Flocks are constituted by a great variety of processes. Major methods of acquiring animals include inheritance, gifts, dowry, exchange, leasing and natural increase. In the pure pastoral system, additional animals are bought with money obtained from caravan operations and from salaried employment. In agriculture-associated systems, the money from sales of crops surplus to subsistence is often invested in livestock. Where women may own livestock, they often obtain them by dowry or by income from sales of milk.

As an investment vehicle, small ruminants are often considered as the small change or credit account of a savings plan while cattle constitute the capital account. Many new entrants to the business of livestock production start with small ruminants. In addition, because of their greater resistance to drought conditions and their faster breeding cycle, small ruminants are the first type of animal to become available and be bought by people with a livestock tradition who, for some reason, have lost their stock.

MANAGEMENT

General practices

Until recently, it was widely considered that no management was practised in traditional herds and flocks. This attitude still prevails in some quarters but even a little thought will show its absurdity. Pastoralists are generally better managers than agro-pastoralists or crop farmers who depend only in small part on animals for their livelihood. Nomadism and transhumance are sophisticated responses to a resource which is always in short supply and often totally deficient. Smallholder fattening is equally a reaction to a long or short term excess of resources and often to a spatially and temporarily restricted demand for meat. These two examples are at the outer limits of a whole range of management practices found across the spectrum of ecological zones from extreme arid to very humid.

Table 4 provides some indications of the strategies ("macro-management") and tactics ("micro-management") of management of traditional owners in Africa. With few exceptions, the tendencies follow a logical pattern from dry to wet zones. These tendencies are: nomadism to fattening; free range grazing to totally confined animals; larger flocks in less favourable to smaller flocks in more favourable areas; and sheep in pastoral to goats in agro-pastoral systems. One of the exceptions is the example of highland central Africa (Table 5; Bizimungu, 1986) where goats are more important in the drier and less intensively cultivated areas. Large-scale modern management systems are generally found in the highland areas of Kenya and Zimbabwe but intensive modern feed lots are increasing in numbers in all areas.

Table 4 Ecology and management of goats and sheep in semi-arid Africa

Ownership patterns

Patterns of ownership in traditional systems differ widely and are often difficult to understand, especially for someone not a member of the owning group. The ramifications of the numerous African extended family systems, the practices involving "stock friends", loans and flock splitting, and sub-letting the flock to a professional herder usually of a different tribe, all lead to a rather vague idea of who owns which animal. Under these conditions, "ownership" changes many times during the life of an animal.

Nonetheless, it is generally true that individual or family ownership is greatest in the dry areas. In West Africa and in Sudan, this essentially means that flock sizes and numbers owned decrease from north to south. In Ethiopia and Kenya, flock sizes decrease with altitude. These trends reflect the systems' differences which change from pastoral in the dry areas to agro-pastoral or agricultural in the better endowed zones.

Table 5 Biophysical characteristics and livestock ownership patterns in highland central Africa

Perhaps of more importance, even though the change has been less well recorded, are the increasing numbers of goats and the increasing numbers of people who keep goats as management systems become sedentary. Goats are generally more prolific than sheep and are possibly easier to manage for people with little experience of animals because they are capable of foraging more widely and on more vegetation types. Table 7 (Mosi et al, 1982) are shown ownership patterns in the humid zone of south-west Nigeria while Table 8 provides additional data for Chad and Kenya.

Table 6 Ownership patterns of sheep and goats in the agro-pastoral area in central Mali

Notes: 1) of all owners i.e. irrespective of whether the holding of one species of stock is nil

2) of only those flocks in which animals are held, i.e. nil holdings excluded

During the last few years (although again official statistics do not yet show this), it is probable that the goat population has increased absolutely and relatively more quickly than the sheep one. This is probably due to the generally higher reproductive rate of goats and their less demanding dietary requirements.

Table 7 Patterns of small ruminant ownership in the humid zone of south-west Nigeria

When calculated on the same basis of unit weight or unit metabolic weight, goats are usually less productive than sheep in terms of meat but their better milk yield makes them a more attractive proposition to livestock owners who keep only a few animals. In traditional systems, it is probable that goats will continue to expand in relation to sheep for the foreseeable future. In modern systems there is still some resistance to goats, especially in Kenya, but even here the attitude is changing and meat goats and Angoras for mohair production are beginning to make their appearance.

Table 8 Livestock ownership (numbers per household) in agro-pastoral and pastoral societies in Kenya and Chad

Flock structures

In earlier times, "prestige" and "perverse supply" were terms often used, usually in a derogatory manner, to describe the behaviour of traditional owners in relation to their animals. African livestock owners are undoubtedly conservative but it is doubtful if they are more so than their counterparts in Europe, the Americas and Australia. Their reasons for keeping stock are rarely irrational and are related to their particular needs either in the long or in the short term. This hypothesis can be supported in regard to the age and sex structure of flocks. Whatever the major objective of the keeping of sheep and goats, there is always a preponderance of females in the flocks while minor differences in sex and age structure are maintained. It needs to be emphasized that almost all animals in the flocks are "productive" whether that production consists of giving birth to young, providing wool or hair, producing milk, or simply undergoing the process of growth to a size at which another product becomes the principal one.

Table 9 provides some examples of flock structure related to production objectives. With the exception of the Afar of Ethiopia (the Afar in Djibouti have a similar strategy) and the case of pelt production in Botswana, all flocks have 70 to 75 per cent of the total as females and about 55 per cent of the flock is comprised of females of breeding age. In five ethnic groups in Mali covering the whole range of systems, females (x ± s.d.) accounted for 74.7 + 3.07 per cent of the flock and breeding females 54.3 ± 2.43 per cent. Contrary to another article of conventional wisdom, there are very few old females in the flocks: in large pastoral flocks, this class of animal is rarely in excess of 5 per cent and in small agro-pastoral flocks it is never more than 10 per cent.

Table 9 Flock structures in relation to management objectives (as per cent of animals)

Figure 7 A Sudan Desert ram in Southern Darfur with a 'Kunan' to prevent breeding

Figure 8 Leather apron to restrict breeding on a Masai buck in a Kenya flock

The major management practice used to obtain this stability of structure is the early culling of males not required for other productive functions. Such young males are sold or slaughtered for home consumption. The numbers of males of breeding age and whose function is reported as "reproduction" are usually, and strictly speaking, in excess of those required: numbers are not excessively high, however, in view of the insurance required against sterile and temporarily infertile males. Other mature males fulfil a productive function whether this is the provision of wool for Macina Fulani, hair for Moors, or fat for Masai. In the humid zones, proportions of females may exceed 80 per cent in the derived savanna areas and 85 per cent in true forest areas. insurance required against sterile and temporarily infertile males. Other mature males fulfil a productive function whether this is the provision of wool for Macina Fulani, hair for Moors, or fat for Masai. In the humid zones, proportions of females may ex- ceed 80 per cent in the derived savanna areas and 85 per cent in true forest areas.

Stratification of flocks is not common in traditional societies. Where breeding control is required it is achieved by a variety of means including the 'kunan' (Figure 7) in northern and western Africa and an apron (Figure 8) in eastern Africa. In some ethnic groups where small ruminants are the principal animal wealth, there exist sophisticated Stratification patterns, one example for the Macina Fulani being provided in Table 10.

Table 10 Stratification of Macina flocks in Mali, with demographic characteristics of each

ADAPTATION AND INTEGRATION OF SMALL RUMINANTS IN AFRICAN SYSTEMS OF PRODUCTION

UTILIZATON OF RESOURCES

Any degree of utilization of the natural vegetation involves modifications to its composition. Such modifications are often referred to as degradation. Where such degradation occurs there is often a gradual change in the combination of domestic ruminant species in favour of small ruminants and in particular the goat. This is one of the. main reasons why goats are blamed for desertification. Small ruminants compete with other domestic species for the resources available. They are however complementary to other species with regard to forage resources consumed and the height at which the forage is found. For this reason higher total biomasses of domestic livestock can be maintained, resulting in higher incomes from livestock production for owners. The production of more than one species of domestic animal enables maximum utilization to be made of grass and browse cover across and within years. An illustration of the complementarity of the two major feed strata in the Sahel zone is given in Figure 9. The browse layer, such as Boscia Senegalensis, is consumed by goats (87 per cent of feeding time being spent on the browse layer) and camels, whilst sheep (59 per cent of grazing time) and cattle graze on the annual grass Schoenefeldia gracilis. In this system in the southern Sahel, crop residues supplement the total forage resources and cattle spend 43 per cent of their annual grazing time on stubbles, with goats and sheep spending1 per cent and 2 per cent of their time respectively. Crop residues are available from January onwards, during the dry season, when the quantity and quality of natural feed resources are mediocre.

Figure 9 Complementarity of biomass production curves in fodder species in the browse and field layers

Table 11 Contribution of different fodder sourees (per cent) to the diet of domestic herbivores in Kenya

Recent surveys carried out in kenya further demonstrate the complementarity of domestic species with regard to the utilization of forage resources. The time spent by each of five categories of livestock on three elements of the rangeland resource are given in Table 11 (Schwartz & Said, 1986). Data provided by a related survey (Figure 10) indicate the feeding height of camels, goats and sheep.

A mixture of species on semi-arid rangelands, for example, makes it possible to reduce the stocking rate of 26 hectares per tropical livestock unit (a TLU is equivalent to 250 kilograms live weight) for cattle alone to 13 hectares per TLU when cattle and goats are reared together and to 10 hectares per TLU when camels are included (Schwartz, 1983). In order to maintain these stocking rates, the ratio of one species to the other in terms of TLU should be 1.0:1.0:0.3.

Figure 10 Feeding times at different heights above ground level by three domestic ruminant species

Goats walk long distances in search of food and feed on a wider range of vegetation types than do other domestic animals living in the same environment (Table 11). Even when they graze at the same height as sheep and cattle, the overlap of species eaten is not very great (Figure 11 and Figure 12). When feeding, goats nibble rather than bite due to the anatomy of their muzzles and jaws. They are selective feeders, eating mainly leaves, flowers and fruits as opposed to stems and other permanent parts of plants. For this reason they cause little damage to the plant structure unless the vegetative biomass is already greatly reduced. Goats ruminate less effectively than sheep or cattle and food passes faster through their alimentary system. Consequently, the seeds of their preferred plant species pass through the digestive tract more or less intact and can easily germinate. Goats may be utilized in this way to seed denuded areas with the types of forages preferred.

Figure 11 Feeding behaviour of four domestic animal species in Kenya in relation to: a. number of species in diet; b. time spent at each feeding station; and c. feeding height

Goats feed mainly on browse plants and when herded together with sheep the latter are often encouraged to do likewise. The phenology of several species of browse found in Africa is such that leaves and fruits with a high protein content are available during the dry season. Consequently, the nutritional needs of small ruminants are less restricted by the seasons. This is reflected in their ability to maintain their weight to within a few per cent of their annual average as compared to cattle (Figure 13). Seasonality of breeding is also less marked than for cattle, this probably also being related to nutritional status.

In zones in which agriculture is an important part of the system, the feeding habits of goats are an additional advantage. They spend less than 30 per cent of the time spent by sheep and only 5 per cent of the time spent by cattle feeding off crop residues (Table 12; Wilson, de Leeuw & de Haan, 1983). This therefore enables cattle to benefit directly from the farming system and also to transfer and convert, through their manure, distant and less utilized resources for the benefit of man.

Figure 12 Dietary range of goats (?) and sheep (?) and relative overlap between the species in a low-bush savanna in Kenya

It has been estimated that the recovery period needed for cattle to attain the number and level of production existing prior to a drought could be as long as 40 years (although the recovery period following the notorious 1968-1973 drought in the Sahel was less than 10 years in most cases). Small ruminants, due to their lower mortality rate, their shorter gestation period, reduced generation period and multiple births which are not seasonal, have a recovery period which is much shorter. In fact, following a severe drought, goats conceive as soon as there is sufficient humidity for the growth of leaves on browse plants, kid five months later, and consequently produce milk for human consumption at a very early phase of the recovery cycle. In numerous instances, they are a source of food before cereals are ripe for harvesting.

Figure 13 Seasonal variations in weight of domestic ruminants in two agro-pastoral sub-systems in central Mali

CONTRIBUTION TO MAN'S WELL BEING

Small ruminants are not only advantageous to man during periods of cyclical and unpredictable food shortages. They are also adapted to balancing the energy and protein supply during normal variations occurring over the years as well as between different seasons.

In Mali, goats provide about half the total quantity of meat sold to consumers living in the towns, the greater part of this being available towards the end of the dry season when there is little beef on the market (Figure 14). In Kenya in a modified traditional system in which veterinary medicines were provided, goats contributed 18 per cent of the minimum calorific requirements (in meat and milk combined) of the human population. They were surpassed by camels (27 per cent) but contributed more than sheep(12 per cent) and cattle (16 per cent), with cereals and other sources (27 per cent) making up the remainder of the diet. In this same Rendille system, goats provided 33 per cent of the minimum protein requirements even though protein availability was in excess of that required. In other regions of Kenya, goats accounted for about 75 per cent of the total meat consumption in pastoralist households (Figure 15 ; Schwartz, 1985).

Table 12 Time (per cent) spent on different fodder sources by three domestic species in central Mali

Small ruminants produce lower absolute quantities of milk than do cattle. Taking into account body weight or metabolic weight, however, their milk yield is higher than other species, with perhaps the exception of the camel. These minor supplies are, when all else fail, available during the most difficult periods of the year as is shown in Figure 16 for the Sudan and Table 13 (Coppock et al, 1982) for Kenya.

Figure 14 Contribution of domestic ruminant species to the meat supply of a central Mali town

At the beginning of the 1970s, the publicity given to the drought in the Sahel focused international attention on the fragility of the food supply system in Africa. The droughts of the early 1980s, which mainly affected Ethiopia but which also affected the Sahel as well as Sudan, have again resulted in famine situations. During both periods, 80 per cent or more of cattle were lost, according to reports, while small ruminant losses did not exceed 50 per cent.

Figure 15 Proportion of goat meat to all meat eaten in 60 Kenya pastoral households

The products obtained from an animal may be expressed as a productivity index. Some generally accepted indices are the live weight of young produced by a breeding female per year, per kg of breeding female per year and per kg metabolic weight of breeding female per year. Some calculated productivity indices are given in Table 14 for Mali for four species of domestic ruminants. These figures, collected over a six year period between 1978 and 1983, clearly demonstrate the relative effectiveness of the short term utilization of each of these species in this environment. The annual and seasonal responses are different for each species, however, and in general seem to complement each other (Figure 17, Table 15). It is evident that fluctuation in productivity is considerably reduced when the livestock holding consists of several rather than of a single species.

Figure 16 The percentage of lactating females of three different species at different times of the year in Sudan

Table 13 Seasonal contribution to human milk supply (per cent) by different livestock species in Turkana, northern Kenya

The major advantages of including small ruminants in mixed species guilds are evident during a prolonged period of drought. The two species of small ruminants appear to withstand drought better than cattle although there exist regional and breed variations with regard to the ability of sheep and goats to do so. Table 16 (Campbell, 1978) provides the figures for cattle, sheep and goats in the region inhabited by the Masai in Kenya following the drought of the mid 1970s. Although the Masai are generally considered to be cattle breeders, the importance of goats and sheep is clearly emphasized by the number of people who keep them. The resumption of breeding by these two species following a drought guarantees food in the form of milk even before cereals can be harvested. In more general terms, the role of goats and sheep as a continuous source of protein during and immediately following a period of drought is demonstrated in Table 17. The overall demand for meat in four West African countries remained constant throughout the drought period but the relative and overall contribution of goats and sheep increased.

Figure 17 Comparative annual and seasonal productivity indices for cattle, goats and sheep in central Mali

Table 14 Productivity indices for different livestock species in Mali

Table 15 Ratios of variation (maximum: minimum) of productivity indices for three domestic species in Mali

Table 16 Effects of drought on livestock in a Masai agro-pastoral system at Loitokitok, Kenya

THE SMALL RUMINANT GENETIC RESOURCE

The majority of goats and sheep in tropical Africa are "indigenous" types. In essence, this means that they have been naturalized for several thousands of years, although both species were originally domesticated in Asia (Epstein, 1971).

Table 17 Contribution of sheep and goats ('000 head) to recorded slaughter in four Sahel countries before and after a drought (per cent of total TLUs)

Recent importations -- in the last 150 years -- of specialized types of small ruminants have been mainly for modern commercial operations. The Republic of South Africa has been foremost in this movement but there are large populations of Merino sheep in Kenya and Zimbabwe and of Karakul sheep in Namibia. Merinos are also important in Lesotho in the small-scale sector, as are Angora goats. Angoras are also gaining importance under commercial conditions in Kenya. Elsewhere, there are relatively small numbers of Karakuls in Botswana, Angola and Rwanda. Attempts to introduce other exotic breeds have generally been unsuccessful but a new composite breed, the Dorper (Dorset Horn x Blackhead Persian), is used for meat production under local conditions, notably in Zimbabwe and Kenya and more recently in Botswana.

It is probably incorrect to talk of "breeds" with regard to African small ruminants but it is evident that identifiable types do exist. The development of these types may be considered as an adaptation to the stresses of the African environment. Selection over the centuries has been on their ability to adapt to local ecological conditions and to meet the production requirements of their owners.

Until recently, blood grouping and chromosome mapping have been little studied but increased interest is currently being shown in this field and it is certain that in the near future some light will be thrown on the relationships between one type of sheep and another.

Figure 18 A castrated West African Long-legged goat in Burkina Faso

Goats

Indigenous goats have been classified into two main groups, the long-eared and short-eared (Mason & Maule, 1960). This is not a particularly useful system and a more appropriate one ascribes goats to large, small and dwarf types (Devendra & Burns, 1983). Large types, which may also have disproportionately long legs (Figure 18) are found along the southern fringe of the Sahara and also in southern Africa; the small types are mainly distributed in eastern Africa; and the dwarf types, which are also to some extent tolerant of trypanosomiasis, are found mainly in humid West Africa (Figure 19). Dwarf types are usually more prolific than the small and large types.

The normal regional distribution and major production aptitudes of some goat types are shown in Table 18. Variation in the productive efficiency of goats is due not only to animal type but also to the environment and management.

Other than meat, skins and milk are the two major products of goat production. Constant attempts have been made to improve indigenous goats by outcrossing to non-African breeds for the production of milk, meat or fibre. These have in general failed except in cases where artificial conditions have been created for the purely exotic types and the progeny of the crossbreeding. Possibilities for improving milk or meat production exist by the utilization of some indigenous breeds such as the Boran or Galla of northern Kenya or the Boer of southern Africa.

Figure 19 Distribution of major goat types in tropical Africa

Table 18 Areas of distribution and production aptitudes of some African goat types

Figure 20 Distribution of major sheep types in tropical Africa

Table 19 Areas of distribution and production aptitudes of some African sheep types

Sheep

African sheep are usually described as thin-tailed, fat-tailed or fat-rumped (Mason & Maule, 1960) and thin-tailed are sometimes further segregated into hairy or woolled types (Epstein, 1971). Thin-tailed sheep are commonest in the northern dry tropics where they are usually of large size or in the western humid areas where they are smaller and often referred to as dwarf or forest sheep. Fat-tailed types predominate in eastern Africa as far south as Mozambique. Fat-rumped types are commonest in traditional systems in north-east Africa, but have spread in commercial systems to Zimbabwe and other countries of the southern region (Figure 20).

The major production aptitudes of African sheep and the general type of environment in which they are found are given in Table 19.

There appears to be little reason at present in Africa to attempt an improvement of sheep by utilizing non-African breeds. In areas of favourable climate, however, as in the East African highlands and Zimbabwe, such an improvement may be justified. An example is the crossing of the Dorset Horn with the fat-rumped Blackhead Persian in order to increase the prolificacy and the growth rate of the latter. Under ideal climatic or management conditions, a direct introduction of exotic sheep could be considered.