Introduction
Strategic research leading to the better understanding of trypanotolerance and utilisation of trypanotolerant livestock, and on the integration of trypanosomiasis control measures into sustainable production systems, has been an ILCA priority from the start. The association with ILRAD in coordinating collaborative research through the African Trypanotolerant Livestock Network exemplifies the value of effective cooperation with NARS. This research has provided the first evidence that trypanotolerance is not only a breed characteristic but also an heritable trait. The large genetic variation identified within the N'Dama breed opens new opportunities for improved productivity through selection for trypanotolerance.
Current Objectives
Research programmes are directed to the improvement of livestock production in tsetse-affected areas of Africa by achieving a better understanding of genetic resistance, acquired resistance, environmental factors which affect susceptibility and the efficacy of control measures, and by ensuring optimal application of both existing knowledge and recent research findings.
A network for trypanotolerance research covers the many aspects involved in the problem of trypanosomiasis and trypanotolerance not possible in one or very few research situations. The Network is the operations unit of ILCA's Trypanotolerance Thrust.
Background/History
Any comprehensive livestock productivity and disease research program for Africa has to contain attention to a better understanding and exploitation of trypanotolerant livestock. ILCA is playing a leading role in international research on the better understanding of factors affecting the performance of trypanotolerant animals and effectiveness of trypanosomiasis control measures by bringing or bridging together basis research done at ILRAD and strategic animal production research done by ILCA with its partners in sub-Saharan Africa (Network participants) and overseas.
Current Programme Descriptions
The African Trypanotolerant Livestock Network was established in 1983 in different trypanosomiasis risk situations throughout tropical Africa. A very large body of data has now been built up on various breeds and their crosses under different levels of trypanosomiasis risk in different ecological and management situations.
A comprehensive description of all Network sites and the standard research methodologies used has been given in the publication entitled “ILCA/ILRAD Trypanotolerance Network; Situation Report, December 1985”. There were 13 collaborative research situations in 10 countries (Senegal, The Gambia, Cote d'Ivoire, Togo, Nigeria, Gabon, Zaire, Ethiopia, Kenya and Tanzania (ILCA, 1986a; ILCA, 1986b).
Description of the approach and results of the first 3 years of research were published by ILCA and ILRAD in 1988 as the proceedings of a network meeting (ILCA/ILRAD, 1988).
The objectives in the first years were to establish baseline values for assessing levels of animal health and productivity in the different situations. This having been achieved, internationally recognized specialists reviewed, at the same Network meeting, their fields of interest and contributed to Network development through evaluation of the results presented by Network scientists. They indicated also subject areas where, in order to maximise subsequent progress in the Network, it would have been advantageous to redeploy some resources, modify or redesign some protocols and design further in depth studies. Aspects considered included the representativeness of Network sites, modifications off of the standardised techniques used, studies to quantify genetic variation for trypanotolerance, and the design of intervention experiments.
As a result of these early evaluations, the research programme is now focused on fewer sites with research being undertaken in greater depth under following themes:
Trypanosomiasis epidemiology, including estimates of tsetse challenge to evaluate the possible contribution it can make in planning for increased livestock production; diagnosis of trypanosomiasis; factors affecting susceptibility, and interactions with other diseases.
Effects of trypanosomiasis on animal performance, reproductive cycle, and milk extraction.
Identification of trypanotolerance traits and their linkages with animal performance.
Definition of selection criteria for trypanotolerance, and estimation of phenotypic and genetic variances of, and co-variance between, trypanotolerance and production traits. Our aims under this theme are firmly anchored in conventional approaches to the genetic improvement of disease resistance, which provide information of direct practical value for animal breeding.
The possibility of marker gene identification as an additional potential tool for the identification and use of more trypanotolerant individuals (with ILRAD).
Biological and economic evaluation of productivity responses to intervention: the aim in this theme is to develop and evaluate control aspects to the point that they are incorporated into packages to be delivered as soon as practical to farmers. It is through this theme that research results are integrated into strategies to improve livestock productivity in tsetse-affected areas of Africa.
Work areas include:
• the use of insecticide-impregnated traps and screens for tsetse control;
• the effect on cattle health and production of using trypanocidal
• the efficacy of nutritional supplementation to reduce the deleterious effects of environmental and physiological stresses on stability of trypanotolerance and productivity under trypanosomiasis risk.
• the introduction of N'Dama cattle in village farming systems in tsetse affected areas of Central Africa where cattle husbandry was not practised in the past.
• development and evaluation of pilot selection programmes based on criteria of trypanotolerance.
Research Situations
There are currently 6 countries where collaborative research activities are under way: Senegal, The Gambia, Cote d'Ivoire, Gabon, Zaire and Ethiopia. Activities in Burkina-Faso at the Centre de Recherche sur les Trypanosomoses Animales (CRTA) and in Kenya are also conducted in liaison with the Network with ILCA inputs at the planning and exchange of results levels.
Operation Approach
Network research situations are tackling the components of trypanotolerance research that they are best equipped to handle in a cost-effective manner. They are grouped to complement each other in terms of disease level, tsetse challenge, livestock breed, and specific production systems: sites in The Gambia at the International Trypanotolerance Centre (ITC) and in Senegal at the Institut Senegalais de Recherches Agronomiques Kolda (ISRA) concentrate on research in nutrition, reproduction and milk extraction under various levels of trypanosomiasis risk; sites at the Societe de Developpement des Productions Animales (SODEPRA) in Boundiali, Cote d'Ivoire, on research concerning interactions between trypanosomiasis and other diseases, tsetse control aspects, and the comparative returns from the use of trypanotolerant cattle and sheep; sites in Gabon and Zaire on genetic and animal breeding aspects under high natural trypanosomiasis challenge; and associated sites in Ethiopia and Kenya on susceptible livestock (ILCA, 1990).
An indicator of the level of collaboration with national or regional partners, is the origin of the 146 different authors involved in the 189 papers, published or submitted for publication, or presented at scientific meetings over the period 1978–1990: 68 were from national organisations, 27 were from ILCA and 51 were from other international organisations in Africa or overseas.
This overview indicates that results from the African Trypanotolerant Livestock Network is providing strategies to improve the productivity of trypanotolerant livestock adapted to the many different environments prevailing in tsetse affected areas of Africa.
ILCA's ability to link international, regional and national organisations into collaborative research programmes providing extensive acces to on-farm experiments throughout the ecological zones affected by trypanosomiasis greatly contributes to its successful achievements in trypanosomiasis research.
Major important results, which will have an impact on the economic development of the agricultural sector, which have been reported at international meetings and in refereed journals include:
In N'Dama cattle a much higher level of milk extraction for human consumption than previously believed, and that milk may contribute to potentially higher revenues for farmers in tsetse-affected areas.
Improved techniques for trypanosomiasis diagnosis contribute to a better assessment of trypanotolerance.
Criteria for, or traits measuring, trypanotolerance are more precisely assessed. So that for the first time, the genetic control underlying trypanotolerance has been demonstrated in N'Dama cattle opening practical possibilities for selection of livestock based on disease-resistance criteria.
Moreover, the integration of technologies into ongoing production systems is now well underway. The most original and likely to contribute to global knowledge as well as to improved livestock production under trypanosomiasis risk will be selection based on trypanotolerance criteria into the relevant production systems.
Training and Information Services
Training has been a vital component of Network activities. Two group training courses per year have been held since 1982 in French and English with the International Laboratory for Research on Animal Diseases (ILRAD) providing training in animal health and tsetse evaluation while ILCA was responsible for the animal production and data handling and analyses aspects.
From 1988 onwards emphasis was progresively placed on courses for individuals or smaller groups in order to tailor training to specific needs arisen from research development. One of the advantages of the organisation was that scientists providing the training where those involved in backstopping field activities.
These training activities have provided major opportunities for the dissemination of information and research results, additional to those provided by ILCA's Training and Documentation Department and by more specialized agencies such as the Food and Agriculture Organization of the United Nations (FAO) and the International Scientific Council for Trypanosomiasis Research and control of the Organization of African Unity (ISCTRC).
Future Outlook
In the near future ILCA will concentrate its efforts in pursuing the planned strategic research in order to be able to propose as soon as possible recommendations for improved livestock production in tsetse-affected areas of Africa.
In order to meet these objectives, the economic research component of the Network activities has now been reinforced to provide basis for economic production of livestock under trypanosomiasis risk.
Important questions remain to be addressed so as to be able to make full use of all genetic resources available in Africa, such as the other trypanotolerant breeds of cattle and other trypanotolerant livestock species. The possibility of genetic variation in the degree of susceptibility to trypanosomiasis among the susceptible breeds of livestock is another areas there research will be pursued because the whole population of trypanotolerant cattle is unlikely to be able to meet livestock population growth required for the future.
Livestock resistance to other diseases or parasites is increasingly given attention as a possible contribution to better health management in Africa. More research is needed on levels of resistance to contribute to an overall improvement of livestock production.
1991–1992 are key years during which major efforts are being put into identifying further research needs which will be part of ILCA's next five-year research plans.
