1. Introduction

Background and objectives

Agriculture is one of the most important human activities in sub-Saharan Africa . Besides being the mainstay of food supply, the agricultural sector is the major source of employment and income. About 67 percent of the region’s human population, which was 601 million in 2000, live in the rural areas and are primarily engaged in agriculture and related activities. Thus agriculture, directly or indirectly, forms an important component of the livelihoods of more than 400 million people in the region.

The contribution of agriculture to the gross domestic product (GDP) of sub-Saharan Africa as a whole is estimated to be 32 percent. Livestock production contributes 25 percent to the region’s agricultural GDP, mainly through meat, milk, eggs, wool, hides and skins. According to Winrock (1992), if non-monetized contributions (draught power and manure) were to be included, reflecting the importance of integrated crop-livestock farming systems, the contribution of livestock to agricultural GDP would increase by 50 percent, bringing the livestock component of agricultural GDP to about 35 percent. Within the rural agricultural economy, livestock remain closely associated with the social fabric and welfare of rural households in sub-Saharan Africa. Livestock play a cushioning role, adding to stability of farm incomes, food security and farming systems. Furthermore, livestock are kept as a form of insurance and a means of storing savings.

Sub-Saharan Africa has one of the fastest growing human populations in the world, with growth rates estimated at 2.6 percent per annum. Yet it also has the world’s lowest per capita consumption levels for livestock products, estimated at 11.0 kg of meat and 27.2 kg of milk in 1999 (the developing world average is 26.4 kg for meat and 48.6 kg for milk). These consumption levels are approximately one seventh and one quarter of those in the developed world. This situation is aggravated in that growth in the production of livestock products in sub-Saharan Africa is not keeping pace with the growth in human population, resulting in declining per capita production in the case of beef and milk and negligible increases for other products (Appendix 1).

The low productivity of the livestock sector is one of the major reasons why only small amounts of food of animal origin are available for human consumption in sub-Saharan Africa. While sub-Saharan Africa as a whole accounts for approximately 14 percent of the world’s livestock resources, it produces only about 2.8 percent of the world’s meat and milk (Table 1).

In order just to keep pace with human population growth, and so avoid declining self-sufficiency ratios and rising import bills, the output of livestock products in sub-Saharan Africa would have to increase by at least 2.6 percent per annum over the next decade. While expansion of the livestock population can contribute to the necessary increase in output, increases in animal productivity are also necessary. In sub-Saharan Africa as elsewhere, livestock are kept in different production systems, which face varying constraints, possess different potentials for growth and have different resource endowments. Differentiation by production or farming system is a powerful tool for communicating conclusions to policy makers (Dixon et al., 2001). The current study focused on ruminants because cattle and small ruminants (sheep and goats) will continue to be the region’s predominant livestock, as they constitute approximately 72 percent and 16 percent respectively to the region’s total livestock resources, expressed as tropical livestock units (TLUs).

Table 1. Tropical livestock units (TLUs) (‘000) and meat and milk production (‘000 tonnes) by region in 1999

¹ The TLU conversion factors used are as follows: cattle = 0.70, sheep and goats = 0.10, pigs = 0.20 and chicken = 0.01

Source: Jahnke et al., 1988. Numbers are taken from FAOSTAT (2000)

The main objectives of the study were twofold:

• to improve the information base on livestock production in sub-Saharan Africa by compiling and reviewing quantitative information on various aspects of sub-Saharan ruminant production systems,

• to estimate the offtake of livestock products from the different systems and their contribution to the availability of livestock products for human consumption.

The study begins below, with an overview of sub-Saharan Africa’s land and livestock resources. Chapter 2 presents a classification of livestock systems in the region, while Chapters 3 and 4 describe traditional and non-traditional ruminant systems. The production parameters of cattle, sheep and goats in traditional and non-traditional systems are reviewed in Chapter 4 and Chapter 5 respectively. The results of modelling these livestock production systems are presented in Chapter 7. Chapter 8 gives a summary and conclusions.

Land and livestock resources

Land area and agro-ecological zones

Sub-Saharan Africa covers a total area of 22.4 million km² and lies almost entirely between the tropics of Cancer and Capricorn.^[1] Following Winrock (1992), it can be divided into four subregions: Central, East, southern and West Africa, which represent 23.8 percent, 27.7 percent, 21.2 percent and 27.3 percent of the total area respectively (Map 1, central section; Appendix 2).

Winrock (1992) classifies sub-Saharan Africa into five agro-ecological zones (AEZs): arid, semi-arid, subhumid, humid and highlands (Table 2). This classification was adopted for this study because it coincides with that used in most published literature on livestock in the region. The basis of the classification is the amount and distribution of rainfall, the altitude (which affects temperature) and the length of growing period (LGP) (Winrock, 1992; McIntire et al., 1992). The potential for livestock production is defined in terms of the carrying capacity measured in TLUs per km². In areas with annual rainfall of 200 to 600 mm, the sustainable number of TLUs is 7 to 20 per km², compared with the highest carrying capacities found in river basins, which range from 150 to 350 per km² (Jahnke, 1982).

Table 2. Definitions of agro-ecological zones (AEZs) in sub-Saharan Africa, land area within each zone and their distribution across subregions

¹ Mean daily temperature during the growing period = <20°C

Source: adapted from Winrock (1992); area calculations from FAO (1999)

The arid zone, which is the largest, covers 38.2 percent of sub-Saharan Africa. It receives between 0 and 500 mm of rainfall per year and has an LGP of less than 90 days. A characteristic of the arid zone is the high variability of its rainfall, which has a coefficient of variation of 25 to 35 percent, according to Wilson (1986a), making it unsuitable for crop production and thus, in principle, exploitable only through livestock grazing. However, some crop production does occur in parts of the arid zone receiving between 300 and 500 mm annual rainfall.

The semi-arid zone covers about 18.1 percent of sub-Saharan Africa, receives 500 to 1 000 mm of rainfall per year and has an LGP between 90 and 180 days followed by a 7- to 9-month dry period. The coefficient of variation of rainfall is generally in the region of 20 to 25 percent (Wilson, 1986a). The main crops are millet, sorghum, groundnut, maize and cowpea. Livestock production, however, still provides much of the value of agricultural output.

The subhumid zone covers 21.2 percent of sub-Saharan Africa, extending through the centre of West Africa to parts of East and southern Africa. It receives between 1 000 and 1 500 mm of rainfall per year. Rainfall is less variable than in the arid or semi-arid zones, making crop production less risky and pastures more productive. A wide variety of crops is grown in the subhumid zone, including cassava, yam, maize, fruit and vegetables, rice, millet, groundnut and cowpea.

The humid zone covers 17.9 percent of sub-Saharan Africa and stretches along the coast of West and Central Africa and into the central Congo basin. The humid zone receives in excess of 1 500 mm of rainfall per year, has an LGP of 270 to 365 days and consists of rain forests and derived savannah.

The highland zone is defined as the area in which the mean daily temperature is less than 20°C. An alternative definition is based on altitude, but this is less useful, according to Jahnke (1982). The highlands occupy about 4.7 percent of sub-Saharan Africa. Approximately 75 percent lie in Ethiopia and Kenya and the remainder in other East African countries and subregions. Rainfall is at least bimodal. The climate, relatively few disease and pest problems, and high productive potential have led to high human population densities and provide a favourable environment for livestock production.

Livestock populations and their distribution by agro-ecological zone

Table 3 (and Appendix 3) presents the population sizes of livestock species in numbers and in TLUs in each of sub-Saharan Africa’s four subregions. The reported livestock population of sub-Saharan Africa in 1999 comprised 191.3 million cattle, 158.7 million sheep, 182.1 million goats, 15.5 million pigs and 700 million chickens (FAOSTAT, 2000). East Africa has by far the largest population, with 55.3 percent of the total TLUs in sub-Saharan Africa, followed by West Africa, southern Africa and Central Africa, with 27.1 percent, 9.4 percent and 8.2 percent respectively.

Table 3. Livestock population in sub-Saharan Africa in numbers (‘000) and in tropical livestock units (‘000) (1999)

¹ The TLU conversion factors used are as follows: cattle = 0.70, sheep and goats = 0.10, pigs = 0.20 and chicken = 0.01

Sources: Jahnke et al. (1988). Numbers are taken from FAOSTAT (2000)

AEZs are one of the most important determinants of the characteristics of livestock production systems, in terms of species, breed, stocking capacity, disease pressure, individual productivity, and so on. Table 4 presents the distribution of ruminants by AEZ in 1999, while the estimated cattle density, and population by zone and region in 1994 are presented in Map 2 and Appendix 4 respectively.

Table 4. Estimated distribution of cattle, sheep and goats (‘000) by agro-ecological zone in sub-Saharan Africa, 1999

Sources: cattle distribution: based on FAO (1999); sheep and goat distribution: taken from Winrock (1992); livestock population: from FAOSTAT (2000)

More than half of all ruminant livestock in sub-Saharan Africa are kept in the arid and semi-arid zones. The lead species numerically in the arid zone are goats and sheep, followed by cattle. Although the lower rainfall areas of the semi-arid zone (500 to 750 mm rainfall per year) are best suited to grazing, livestock production in this zone is usually a component of mixed smallholder crop-livestock systems. The semi-arid zone has cattle as its lead species (with 30.6 percent of all animal numbers), followed by goats and sheep. In the subhumid zone, livestock production is undertaken in mixed crop-livestock systems. Cattle are the lead species, followed by goats and sheep.

Although the potential for livestock production is high in the humid zone, it is not an important economic activity here because of disease constraints, primarily the predominance of trypanosomiasis (Wilson, 1995). Only 6.1 percent, 8.3 percent and 9.6 percent of sub-Saharan Africa’s total population of cattle, sheep and goats are found in this zone, despite its constituting 21.2 percent of the region’s land area.

The highlands have the region’s highest density of both people and animals (19 percent of TLUs, but less than 5 percent of land area) (Table 5). Livestock are kept mainly in smallholder crop-livestock farms. Animal traction is widely used in Ethiopia and Madagascar, is less common in Kenya and the United Republic of Tanzania and is hardly used at all in Rwanda, Burundi and the eastern part of the Democratic Republic of Congo. The main reasons for non-use in these areas are the small size of farms, their topography and the predominance of coffee, banana and other perennial or semi-perennial crops (McIntire et al., 1992).

Table 5. Cattle and human population per square kilometre in sub-Saharan Africa, 1999

Source: calculated from FAO (1999)