PRINCIPLES FOR INDIGENOUS ANIMAL IMPROVEMENT IN THE TROPICS - AFRICAN EXPERIENCES WITH SHEEP AND GOATS

L.O. Ngere 1/

1. INTRODUCTION

The Inter African Bureau for Animal Resources (IBAR) estimated the cattle, sheep and goat population in Africa in 1981 as follows:

These represent about 13% of total world cattle and about 25% each of its sheep and goat populations. Phenotypically, the African sheep and goats exhibit great variation in conformation, coat colour, size, height, length and size of tail, presence or absence of horns and their shape, and behaviour patterns, among others. The different breeds of sheep and goats appear well adapted to the various ecozones found in Africa within which they are widely distributed. The management system in most of Africa is extensive with most of the animals having the natural grasslands and browse, as available, to sustain themselves. The small ruminants also have a variety of use for the indigenous populations. The more conventional includes their utilization as a source of milk, meat, skin, wool; but there are also less conventional socio-economic uses: dowry, cash, sacrifices etc., especially in the rural communities.

2. IMPROVEMENT OF AFRICAN SHEEP AND GOATS

The numbers of African sheep and goats are considerable and a first step in the rational use of such a large collection of animals would be to organize them into smaller manageable groups. This need has been recognized and attempts have been made (Epstein, 1953; Mason, 1951; Mason and Maule, 1960) using easily distinguishable phenotypes of body size and height as well as ear shape and length. Thus, with information from their works, Tables 1 and 2 have been built up showing over 48 breeds of sheep and 22 breeds of goat in Africa. Although the classifications were on a phenotypic basis, simplification of the African sheep and goat fauna was achieved and future studies may reveal even more important underlying genetic differences between the breeds.

In discussing any animal improvement scheme, the environment is important. Africa is a large continent and although the bulk of its area lies within the tropics, the southern and northern tips are within subtropical, and Mediterranean climates, respectively. And the tropics are not one uniform environment - though characterized by high ambient temperatures, trade winds and other geophysical factors influencing rainfall which in turn, being seasonal, affects vegetative cover on which the ruminant stock of sheep and goats largely subsist. This is particularly important in extensive systems under which most of the small ruminants are kept in Africa. The ecozones can be grouped into: Arid, Semi-arid, Sub-humid, Humid, Highlands, and Mediterranean. These zones offer differing opportunity for grazing/browse, can influence parasites which cause disease of the animals, and also affect the comfort of the animals themselves - all these are factors which influence animal productivity and so merit consideration.

Table 1 AFRICAN BREEDS OF SHEEP

Sources: Mason,1951; Mason and Maule 1960.

Table 2 AFRICAN GOAT BREEDS

Source: Mason, 1951; Mason and Maule, 1960.

From the foregoing, animal productivity can be improved either by ameliorating adverse environment, for example, through better nutrition (improving browse/grazing), shelter, health care management of these resources or through genetics. It is only the last mode of improvement that will be considered, in the context of course, of the African environment.

The general principles of animal improvement are well known and there is no reason why it should be different for the African continent. There are, however, some peculiarities of sheep and goat production circumstances in Africa that should be noted:

1. Large numbers of stock (or genetic material) and paucity of information.
2. Generally non-specialized/multiple use of these stock, i.e. for meat, milk, hides and skins.
3. Great range of the environment with the breeds appearing to be well adapted to their particular econiche.
4. Dominance of the extensive system of husbandry in which the animal feeds on whatever the environment provides, and when it can.
5. Poor control of the breeding animals.
6. Systems of flock rearing which may constrain the use of particular breeding plans.

Given such circumstances, plans for genetic improvement of sheep and goats should involve the following:

1. Characterization/documentation of existing sheep and goat resources in Africa, as well as their econiche and management system.
2. Selective breeding or within-breed selection.
3. Crossbreeding of suitable breeds to optimize production.
4. New breed development.

These are not new techniques, but the opportunities they hold for African sheep and goats and examples of their application as well as the problems of their use will be discussed further.

As regards information on sheep and goat resources, work has already begun. FAO and UNEP are collaborating with OAU/IBAR in the establishment of Regional Data Banks and lists of descriptors have been prepared and their methodology and problems discussed at an Expert Consultation meeting in Rome in June 1985. In supporting the establishment of such banks the OUA/IBAR Expert Committe group emphasized, among others:

-	the need to identify and characterize breeds throughout the continent;
-	identify these with high potential;
-	help to encourage the development of good record keeping and centres for breed development;
-	assemble performance data on prolific sheep and goats of Africa.

There are of course some problems with developing data banks not least of which are what information to record, and how to record so as to optimize usage. In Africa the situation is further complicated by the low literacy rates of the livestock farmers, the majority of whom cannot read or write, and the way the sheep and goats are more often left to fend for themselves or are bush grazed. Most of the information will, therefore, come from research scientists, and from fewer animals maintained under systems considerably different from what obtains for the bulk of the population.

Good records of performance form the bases of selective breeding since selection by sight will result in slow, if any, genetic progress. In recording performance, the economic traits need to be focussed upon. For the sheep and goats, these include:

1. Measures of reproductive efficiency, including number of and weight of lambs/kids weaned per ewe/doe joined per year.
2. Mortality at all ages especially from birth to weaning.
3. Measures of growth: birth, weaning and later period weights.
4. Milk yield, where appropriate.
5. Wool quality and quantity, where applicable.
6. Carcass quality.
7. Disease data.

Mason and Buvanendran (1982) have detailed procedures and data that can give information on these economic traits for sheep and goats in the tropics. The close adaptation of African sheep and goats to their habitats would suggest that until more is known of their characteristics much emphasis should be placed on this avenue, i.e. within-breed selection for genetic improvement. Unfortunately, records of performance which form the basis of this technique are still not much developed in most African countries. However, there is an acute awareness of this deficiency and most countries have embarked on development of sheep and goat performance recording schemes at local and national levels, and are collaborating at international levels. Those records when analysed should help herd management, identify superior stock and generally lead to improvements in sheep and goat production in the African region. The data so far available show that African sheep and goats are valuable genetic resources. Thus:

1. The West African dwarf (Mason, 1980) and the D'Man of Morocco (Lahlu-Kassi, 1983) have been identified as highly prolific breeds of sheep.
2. The dwarf breed of sheep and goats of West and Central Africa have been noted to be trypanotolerant (FAO/ILCA/UNEP, 1980).
3. Some goat breeds are reputed to be good producers (Devendra and Burns, 1970).

and more valuable breeds will be identified in the future. In addition records of performance can help identify constraints to productivity and suggest appropriate modes of intervention. But recording performance under the prevailing extensive management of large flocks or in small household flocks will not be easy. Therefore, cooperation between small herds or organization of larger herds probably by governments will enhance the use of this technique. Alternatively, improved breeds (e.g. males developed at breeding stations) can be used on traditional local flocks. The observation by Van Vlaenderen (1985) in northern Togo regarding improvements in productivity in traditional herds using selected rams supports this view. Some improvement programmes in North Africa (Lahlu-Kassi, 1983) of sheep have been planned along such lines.

Crossbreeding is a valuable tool for livestock improvement when properly used. The present knowledge of African sheep and goats as well as the level of husbandry does not permit a general adoption of this technique at this time. When more is known about our breeds one can foresee the use of crossbreeding for systematic exploitation of heterosis in 2, 3 or 4 breed combinations or as a foundation for new breed development incorporating valuable genes from identified superior breeds.

South Africa, though subtropical, has evolved new breeds to meet specific needs:

Goats: Boer; from local goats x European, Angora and Indian types. Inasmuch as all these new breeds were evolved from inputs of indigenous African breeds, repeat of similar schemes is possible. Infact, Ngere (1973) and Ngere and Abeagye (1981) have described the Numgua Blackhead evolved from the West African dwarf x Blackhead Persian in Ghana.'

In conclusion, there is need for more detailed and extensive documentation on performance characteristics of African sheep and goats. Selective breeding (within breeds) would seem to be the most favourable method for the moment.

Any scheme to improve the small ruminants should take into account the habitat and flock sire. Crossbreeding and breed development also have a place under improved husbandry conditions and in the more developed countries of Africa.

REFERENCES

^1/ Animal Science Dept., University of Ibadan, Ibadan, Nigeria.