PRINCIPLES FOR INDIGENOUS ANIMAL IMPROVEMENT IN THE TROPICS

CONSERVATION OF THE KENANA BREED IN SUDAN

E.P. Cunningham 1/

1. INTRODUCTION

Sudan is the largest country in Africa. It has approximately 20 million people, 20 million cattle, and a GNP per head of population of $500. At present growth rates, the population will double in the next 30 years. The country therefore faces enormous challenges in the most fundamental element of economic development - food supply.

In meeting this challenge, the development of the potential of the cattle population is a major factor. The various cattle breeds and types in the country have so far been relatively untouched by modern crossbreeding, immigration or selection practices. They have, on the other hand, been subjected to natural selection in a domesticated environment for many centuries. The two best defined breed types within the national population are the Kenana and Butana. These breeds will inevitably be subjected to substantial pressures from outside genetic sources in the coming decades. The Government of Sudan therefore faces the same difficult task as confronts authorities in other countries in the developing world: how to balance conservation of the undoubted merits of these breeds with the opportunity and necessity for rapid economic development. To help in the resolution of these questions, FAO commissioned a study of the alternative strategies for the conservation of these breeds in 1983, and this report is based on the results of that study. The report concentrates on the Kenana breed, because it was considered to be most immediately in danger.

2. THE KENANA BREED

There are estimated to be about 3 million Kenana-type cattle. This definition includes populations known locally as White Nile type. They are found largely in their traditional areas of origin, the plains adjacent to the White and Blue Nile rivers, in an area stretching south from Khartoum to the Ethiopian border (Figure 1). This ecological zone is typically a low rainfall savannah area, with high temperatures and low humidity. Traditional cattle systems in the area involve seasonal migration, though not to the extent of the true nomadism found further west in Sudan. Since the 1920s, about 1 million hectares of irrigated land has been developed in the area, largely for cotton production. The availability of crop residues and the growing of forage crops have led to greater stability in the cattle population. in the last two decades, the rapid expansion of Khartoum, Omdhurman and Wad Medani has increased the local demand for milk, and stimulated the initial development of commercial milk production. This has led to some crossbreeding, mainly with imported Holstein-Friesian semen.

The Kenana is a true Bos indicus or zebu type. Its origins are not known, but it has been suggested (Boyns, 1947) that they were introduced many centuries ago with migrants from Asia.

The location of the Kenana area within Sudan, and the estimated breed distribution are both shown in Figure 1.

Fig. 1.LOCATION AND ESTIMATED DISTRIBUTION OF KENANA CATTLE IN THE SUDAN.

Production data on the breed in its native environment are difficult to find. The Agricultural Research Council (1975) reported that a sample of the population contained 82 percent females and 18 percent males. The percentage of cows in milk was found to be 37 percent, and average daily production was estimated to be 2 kg. The calving rate was given as 70 percent and mortality was estimated at 5 percent in adults and 10 percent in calves.

The fact that the environment is extremely limiting was illustrated by the work of El-Khidir et al., 1979. They reported that a control group of Kenana heifers had a daily gain of 138 g and calved at 47 months, while a parallel group given extra nutrition had a gain of 470 g per day and calved at 32 months.

The most extensive recorded performance data come from research stations of the Animal Production Research Administration, Nishishiba (near Wad Medani) and Umbenein (near Singa). These data have been summarized and analysed by Fangaly (1980) and some of his results are given in the following table.

Table 1 AVERAGE MILK YIELD, CALVING INTERVAL AND AGE AT FIRST CALVING IN KENANA COWS IN TWO STATIONS (Fangaly, 1980)

3. PRODUCTION SYSTEMS

Conservation or development plans must be considered in the context of the production systems in which they are to be implemented. In the case of the Kenana breed, it is clear that more than one system will apply in the future. At one end of the spectrum, there are Kenana cattle involved in pure nomadic systems, in very stressful environmental circumstances. At the other end, there is the development of a relatively modern milk production sector to service the urban requirements of the country. This range of production systems is categorized in Table 2. In each case, appropriate breeding systems are also indicated.

Table 2 CATTLE PRODUCTION SYSTEMS IN SUDAN

From experience in other countries, and also in Sudan, it is clear that breeds like the Kenana will not be used in their pure form in the more intensive dairy production systems. Most existing city supply producers, even in considerably less intensive production systems, are at present involved in crossbreeding, largely with Holstein-Friesian. In these circumstances, some producers will continue grading up to the exotic strain, while for many the use of half of three-quarter bred exotic bulls will permit the development of synthetic grades, usually more than 50 percent exotic in genetic background.

In the third level, there are many settled farmers in the Khartoum and Gezira areas now beginning to produce milk for sale, though in conditions where cow nutrition and management are often poor. In these circumstances, some will continue to use Kenana cows, but the tendency is to involve some exotic genes also.

Developments in all three of these levels of milk production threaten the existence of the Kenana. Since these populations are largely crossbred, it is impossible to base a conservation programme for Kenana on them. Kenana genes will, of course, survive for some generations in the crossbreds. If synthetic populations are developed, some of the genetic material of the native breed may survive in this form indefinitely. However, even in this case, planned conservation of genetic background of the native breeds is not possible.

At the other end of the scale, large numbers of animals are involved in true nomadic systems. Imposing any kind of external selection programme on animals involved in such systems is extremely difficult for a number of reasons. Because the environment is demanding, and food supply irregular, overall reproductive rates tend to be low. Because animals are so much on the move, regular contact with the herds and their owners, necessary for any kind of consistent selection scheme, is difficult to maintain. Finally, it is questionable if the selection goals of higher milk or meat output from individual animals are desirable in such populations, since the primary requirement is the physiological resilience to cope with the demands of the system. While amelioration of the environment (e.g. by control of parasites and disease, and by improving the feed supply) is highly desirable, it is difficult to envisage the operation of a useful breed improvement programme within the population.

Where the environment is somewhat less stressful, many cattle are involved in systems which are a mixture of settled and migratory patterns. Thus, in the Singa area, some of the stock migrate seasonally to areas where crop residues are available. As with the nomadic systems, these transhumant patterns of farming should also be based entirely on indigenous breeds. For the same reasons, but in a lesser degree, it is difficult to see a development or selection programme operating in such circumstances.

Finally, there are large numbers involved in what are essentially settled farming systems, but systems which are still largely traditional in many respects. They are not involved in commercial milk sales through organized channels. Productivity levels are not particularly high, and the feed supply situation is not likely to permit rapid changes from that position.

It is in this sector, where the indigenous breeds have a relatively secure place in traditional though settled production systems, that the best opportunities lie for introducing a conservation and development programme.

4. CONSERVATION PLAN

The scheme proposed for the Kenana population is outlined in Figure 2. Its essential elements are a consistent selection programme carried out within the herd at Umbenein Research Centre, combined with an annual round of selection from village herds. Technically, this kind of structure is known as an open nucleus system (James, 1977). The primary selection goal should be milk production, defined as yield of fat-corrected milk per lactation. Attention will also need to be given to weight for age, udder conformation, and beef potential. Prior to the commencement of the scheme, a written, agreed definition of the breeding goal will need to be developed.

5. SELECTION IN THE FIELD

Since no records are kept by the herd owners, this selection will have to be on the basis of inspection, together with perhaps some on-the-spot measurement of milk output. These selections should be carried out by a qualified officer of the Ministry. Since a large element of judgement will be involved in these selections, it is essential that consistency is maintained in the judgements exercised.

The procedure envisaged is as follows. In each season, a campaign of visits to village herds would be planned. The aim of the campaign would be to select and purchase for recruitment to the Umbenein herd approximately 20 outstanding cows. Some number between 20 and 50 village herds would need to be visited. In each village, the bulk of the cows can be fairly readily inspected as they move out to grazing in the morning. The officer would identify a few cows (perhaps 3) which he regarded as the best, and during the day would make contact with the owners of these cows. As the herd returns in the evening, his assistants could be preset at the milking of these particular cows, and weigh the milk produced. Some objective measurements (e.g. wither height) would be taken, and on the basis of all the information available to him, the officer would attempt to purchase the best one or two animals. In making these selections, attention would be concentrated on cows in the first three lactations.

FIGURE 2: SELECTION SCHEME INVOLVING VILLAGE HERDS AND GOVERNMENT STATION.

In operating this scheme, there are several imponderables. Since the selection is largely a matter of judgement, it is difficult to predict how effectively it will identify superior cows. However, similar schemes applied consistently in the early days of the formation of the European dairy breeds appear, in retrospect, to have been reasonably successful. It is also difficult to know in advance what success there will be in persuading herd owners to sell (or lease) their animals. A process of trial and error may be necessary to develop a procedure which works well.

6. SELECTION IN THE STATION

While the selection in the field must be done entirely without documented performance records, the opposite is the case in the research station. Here, the necessary scientific and technical personnel are available, together with any equipment required, and the primary purpose of the Centre is the assembly and use of objective data on the cattle herd. Detailed records can therefore be kept of all aspects of reproduction, growth, production and behaviour of all animals. The protocols at present in operation in the herd cover the obvious and immediate requirements (gestation length, birth weight, body weight at suitable intervals, mortality together with causes, breeding age, age-at first calving, milk production, and subsequent lifetime reproductive and production records). In order that the substantial commitment to the new development and conservation programme is justified, it will be necessary to review all of these procedures to ensure that suitable levels of precision are aimed at in the different measures, and that absolute reliability of. data can be guaranteed. In addition, there should be provision for extending the range of characters measured to include suitable metabolic indicators, and, as may be feasible, records of response to parasitic infections both internal and external, together with various tests related to disease resistence. Furthermore, objective measurements of temperament and dairy conformation, dairy traits (particularly udder functionality), such as have been developed for dairy breeds elsewhere in the world, should be applied.

Most of these secondary traits will play a minor role in the selection programme, and it is not therefore an essential point that they should be fully developed in the first few years of the programme. Nevertheless, since the primary motivation for the conservation of the Kenana breed is the presumption that it has some advantageous physiological differences from other breeds, and since there is a great lack of information on such characters in this breed, and in zebu cattle generally, the encouragement of physiological and metabolic studies on the herd is strongly recommended.

The selection goal in the herd should be the same as that in the field programme, albeit with more detailed and objective measurements on which to base selection. Again, an agreed, consistent selection goal needs to be defined in advance, and the criteria and levels of selection also need to be predetermined. Since milk production will be the most important trait in this selection goal, it is possible to draw on studies elsewhere to make some advance estimates of the likely rate of improvement for this major trait. in a closed herd of adequate size to minimize inbreeding effects, annual rates of improvement of between 1 and 2 percent are achievable. In an open nucleus structure, as proposed here, the rate of improvement could be significantly greater.

As is suggested below, some additional studies to guide the selection procedure, and to explore the way in which it depends on the herd and population structure, are justified.

While it is unlikely in the years immediately ahead that any extensive use of embryo transfer techniques can be used in the herd, it should be kept in mind that at some future date the introduction of these techniques could significantly assist the programme. The primary benefit to be derived from the introduction of embryo transfer would be the intensification of selection on the female side which it makes possible. Since each selected cow can, under embryo transfer, provide multiple calves per year the selection exercised on the cows can be that much more stringent. This has particular relevance in the Kenana breed, since it is female performance which is the main criterion for selection.

One of the great difficulties experienced in Umbenein, and indeed in similar stations in other tropical countries, is that because of inadequate and uncertain forage and feed supplies, growth of heifers tends to be very slow, with age at first calving frequently exceeding five years of age. The same causes lead to long calving intervals. The net effect is that too few females are reared in relation to the herd size to permit much selection either in the incoming females, or among the cows in the herd. The statistics of the Umbenein herd in recent years indicate that, as at present operated, it would have some difficulty in carrying out an effective selection programme. It will therefore be essential that a new regime of feed and fodder supply be developed for the station. The work of El-Khidir et al., 1979 has clearly shown that growth and puberty rates can be dramatically improved with adequate feed. In the new provisions, therefore, adequacy and security of fodder and feed supply will be essential.

7. SUPPORTING STUDIES

There are considerable deficiencies in the data base required for the development of future breeding plans for the Kenana breed. The following are some areas which require further investigation:

1. Estimates of population size, sex and age distributions in the Kenana population are tentative. In addition, field productivity is not well documented.

2. Information on migratory patterns in the Kenana population is limited and becoming out of date.

3. The evolutionary and historical background of the breed is relatively unknown. It would be worthwhile to measure the genetic similarity between Kenana and Butana, and to compare both breeds with other zebu and non-zebu cattle populations. Such a study could be undertaken using electrophoretic techniques, and perhaps DNA hybridization techniques also.

4. A critical comparison of the production potential of the Kenana and Butana would clarify which population merits greatest attention in the future.

5. A further study is required of the possible rates of genetic change achievable in the open nucleus type of structure proposed here.

6. Since inevitably a section of the Kenana breed will be involved in crossbreeding with European-type cattle, some systematic experiments are required to measure the additive and heterotic differences between Kenana and the selected European breed.

REFERENCES

^1/ The Agricultural Institute, Dublin, Ireland.