Since its inception in 1984 and official opening in 1987, ITC has made significant contributions to the understanding of trypanotolerance and the factors that affect its expression. This work has been carried out in collaboration with ODA, ILRAD, ILCA, The University of Berne, the UNDP/FAO Regional Project (RAF/88/100) and ISRA (Institut Sénégalais de Recherches Agricoles) and is summarised as follows:
1. GERMPLASM ENHANCEMENT AND BREEDING
Continued progress has been made towards the development of a pedigree N'Dama herd at ITC which is superior in resistance and productivity and in which the selected bulls have also been demonstrated to be highly trypanotolerant as measured by their response to trypanosome infection. In the pedigree herd, growth rates to weaning in excess of 0.5 kg per day, milk production in the region of 1500 litres in 9 months, adult females of 350 kg and bulls of 500 kg have been attained. This level of productivity is remarkable when considered in the light of the widely held opinion that the N'Dama do not produce significant amounts of milk, and the average weight of an adult female in the village is just over 200 kg. These results achieved in the ITC pedigree herd would suggest that the N'Dama could make an excellent multipurpose animal for the region in terms of meat, milk and traction. This work has been facilitated by access, through NARS, to 50,000 village cattle in the study area and 2,000 on-station for breeding purposes and controlled experiments.
A Zebu herd has been established, F1 Zebu/N'Dama crosses have been generated and an evaluation of the trypanotolerant status is being conducted. Initial results show that the productive performance following trypanosome infection, i.e., the degree of trypanotolerance of the F1 Zebu/N'Dama crosses is intermediate between pure-bred N'Damas and Zebus.
Djallonke sheep and West African Dwarf goats have been evaluated for trypanotolerance and their role in the local socio-economic infrastructure investigated. Following both field challenge and experimental infection, a remarkable degree of trypanotolerance was demonstrated. Both sheep and goats continued to be productive despite infection with trypanosomes that can kill Zebus. However, it was found that the criteria used to identify trypanotolerance in cattle, namely the capacity to control parasitaemia and to resist the development of anaemia following infection, are not appropriate for sheep and goats. It was noted that it was women in the region who appeared to play the main role in the maintenance of sheep and goats and the sale of their meat and milk.
On station pedigree herds of Djallonke sheep and West African Dwarf goats have now been established. Each herd comprises of approximately 60 animals.
2. LIVESTOCK SYSTEMS
A major survey involving the regular monitoring of N'Dama health and productivity characteristics under different management systems and trypanosome risk ranging from low to high in The Gambia, and assessment of other diseases constraints, has extended over 5–6 years. This involved 60 village herds and 4,000 ear-tagged cattle, and recorded milk off-take from 1,500 cows over 2,000 lactations, year-round morbidity and mortality, body weight and reproductive performance and disease incidence. Similar work in Senegal involving 6 villages and over 700 cattle has extended the work regionally during the past 3 years.
It was found that the level of performance in the village herds was lower than in the on-station herds in The Gambia but higher than some on-station herds elsewhere in the region. At the same time, the importance and the extent of milk production was demonstrated, with some village animals producing in excess of 1400 litres after 10 months lactation period, including milk required for calf growth. It was shown that the major constraints to production were related to poor nutrition in the dry season, the physiological stresses of lactation and suckling, and to the level of disease risk, the higher the level of tsetse challenge the poorer the performance. It was confirmed that the main disease problems in the N'Dama cattle in The Gambia and Senegal were trypanosomiasis and helminthiasis. Ticks and tick-borne infection and dermatophilosis were only significant in the Zebu herds.
It was of interest that some 30,000 animals of the 300,000 national herd, i.e., 10%, were used for traction.
3. ANIMAL NUTRITION AND FEED
Analysis of seasonal variations in the nutritional values of grasses, browsed forage, legumes, herbs and shrubs, and of the quality of crop residues and by-products has been made. The role of these materials in reducing the deleterious effects of trypanosomiasis, especially during the dry season, and as supplements to promote increased milk production, reproductive and growth rates and accelerated attainment of puberty has been demonstrated.
Strategic supplementation studies have shown that even only small amounts of crop residues can dramatically enhance resistance to disease, increase milk production and growth rates, and improve reproductive performance.
It is now clear that the interaction between genetic resistance, disease and malnutrition is a critical factor in the region.
Certain aspects of the reproductive physiology of male and female N'Dama cattle have been studied, the quality, variability and preservation of semen examined and artificial insemination performed successfully. Embryo transfer from the Gambia to Kenya has been successfully carried out. All of these investigations are essential prerequisites to the eventual expansion and dissemination of the pedigree herd.
5. LIVESTOCK DISEASES
5.1 Tsetse-borne diseases
A series of field and on-station investigations have compared the susceptibility of N'Dama and Zebu cattle to natural field challenge and experimental trypanosome infection. All have confirmed the superior resistance and performance of N'Dama cattle following infection, although variation was observed with both breeds. These findings were further confirmed when N'Dama cattle transferred as embryos from The Gambia to Kenya were found to be remarkably genetic resistant to trypanosomiasis when compared with Kenyan Boran cattle.
A uniquely comprehensive study of tsetse distribution and challenge, disease status, nutritional input and productivity in The Gambia has been completed, the results of which have been correlated as follows:
the varying prevalence and significance of trypanosomiasis in trypanotolerant cattle,
the seasonal variables such as the numbers of flies and their infection rates,
changes in the nutritional status of cattle and the pathognomonic and socio-economic significance of their traditional migratory herding patterns,
the epidemiology and production losses associated with trypanosomiasis (2. Livestock Systems).
These activities are now being expanded into the sub-region.
Current work involves the interrogation of ITC's comprehensive database for the purpose of:
identifying selection criteria for the improvement of the trypanotolerance germplasm in terms of resistance and performance. These activities involve both on-station and village herds,
further developing the disease surveillance methodology and predictive models already produced by ITC.
5.2 Tick-borne and tick-associated diseases
In 1988, a serological and experimental study on N'Dama cattle indicated the absence of appreciable infection rates with both Anaplasma marginale and Babesia bovis. The absence of the former could not be explained in view of the presence of many vectors and it is postulated that it may be due to a resistance factor. Subsequently, it has been found that the Zebu herds at ITC, in contrast to the N'Dama herds, are highly susceptible to tick attachment, dermatophilosis, tick-associated mastitis, as well as vector-transmitted virus infections. These important observations will be further investigated in both field and station studies.
5.3 Endoparasites in rumínants
Research on the epidemiology and pathogenic significance of gastro-intestinal helminthiasis, on-station and in village herds has clearly delineated a largely unexpected source of morbidity and mortality. Experimentally, the deleterious effect of trypanosomiasis on susceptibility of haemonchosis has been shown.
At the same time, preliminary strategic experiments have demonstrated the superior resistance of N'Damas to helminth infections when compared with Zebus.
6. SOCIO-ECONOMIC RESEARCH
A pilot study has been undertaken to provide background information on the role of livestock in rural Gambian households of varying socio-economic status and ethnic origin.
Specifically, this was concerned with their contribution to farm welfare through:
The role of livestock in the agricultural sector has been further emphasised by the fact that many livestock owners now rent herds of cattle to farmers to fertilise their fields, particularly in relation to cash crops.
ITC staff have implemented a training programme in collaboration with the UNDP/FAO Regional Project on the 'Promotion of Trypanotolerant Livestock in West and Central Africa' for veterinarians and field workers from both french and english speaking regions. Since 1988, five such courses have been organised on ‘Production and Disease Control of Trypanotolerant Livestock’, involving 52 staff of the National Agricultural Research and Extension System of the 19 countries in the region.
ITC together with the FAO/UNDP Project have also established a Centre for the documentation and dissemination of information on trypanotolerant livestock.
8. LOCAL, REGIONAL AND INTERNATIONAL LINKS
Following the establishment and consolidation of its activities in The Gambia and Senegal, ITC has now laid the foundation for the implementation of its research programme in the region, in close collaboration with sub-regional organisations and the NARS. Collaborative agreements have been signed with the Mano River Union covering Sierra Leone, Liberia and the Republic of Guinea, while a bilateral agreement with the Republic of Guinea Bissau has recently been concluded. A proposal for collaboration with the Institut Sénégalais des Recherches Agricoles (ISRA) of Senegal and the Interstate Veterinary School in Dakar which provides training for all the francophone countries in West and Central Africa, is being finalised.
ITC also has links with several CGIAR institutes (ILCA, ILRAD), overseas institutions in Europe, America and Asia, as well as other African Research Centres such as the Centre de Recherches sur les Trypanosomes Animales (CRTA) in Burkina Faso. In view of the complementarity of the research on trypanotolerant livestock at ITC and CRTA, the two institutes have signed a formal agreement for coordination and collaboration through regular consultations and harmonisation of research protocols.
FUTURE RESEARCH PROGRAMME OF ITC
The future research programme of ITC will continue to place emphasis on N'Dama cattle, but also on other cattle breeds of main importance in the West-African region, e.g., West-African Shorthorn (Baoule, Muturu) and other breeds, through collaborative agreements with other research Centres and Stations of the region (CRTA in Burkina Faso, Boke in Guinea, Kolda in Senegal).
More attention will also be given to trypanotolerance and disease control in sheep and goats because of their increasing importance and potential contribution to the welfare of the poorer rural population.
The main research activities will include:
1. ENHANCEMENT OF GERMPLASM OF TRYPANOTOLERANT CATTLE
Development and improvement of the ITC pedigree herd will be continued through selective breeding based on an “Open Nucleus Breeding Scheme” using village cattle selected from the data base. Other elite herds will be set up at selected sites in the region for use as foundation stock for livestock development in the sub-humid tsetse-infested zones, e.g., Boke and Kolda, as well as at ITC.
2. LIVESTOCK SYSTEMS AND SOCIO-ECONOMICS
Monitoring of N'Dama productivity characteristics, trypanosomiasis risk and disease constraints will be extended to the region, with cooperation of NARS. The data on crop/livestock systems in the zone will be collected and extended to socio-economic aspects. It is planned to carry out the same investigations on sheep and goats that have been and will be carried out on cattle. Special attention will be paid to animal traction systems using trypanotolerant cattle in order to promote integration between agriculture and livestock in the rural areas facing increasing pressures on land and forage resources.
3. ANIMAL NUTRITION AND FEED RESOURCES
Field observations on the seasonal incidence of trypanosomiasis in The Gambia and experimental results at ILRAD have shown that the pathogenic effects of trypanosomiasis in the N'Dama can be greatly reduced by improved and adequate nutrition. This premise will be thoroughly investigated at both village and station level as a prerequisite to the development of improved feeding systems for trypanotolerant livestock.
The use of local agricultural by-products, multipurpose trees and grasses will be studied, as well as conservation methods for forages, in order to establish socio-economically and ecologically sustainable feeding strategies for trypanotolerant livestock.
Investigations will be carried out on the reasons for the low fertility of many trypanotolerant cattle and small ruminants under village conditions. The influence of trypanosomiasis on reproductive efficiency, particularly during early gestation, will also be undertaken.
Artificial insemination will be initiated and adapted to local conditions in the region in order to facilitate a large scale diffusion of selected livestock throughout the region.
Embryo transfer technology will also be developed, not only to diffuse selected N'Damas but also to produce sibs, half-sibs and twins to be used in genetic studies on trypanotolerance.
5. LIVESTOCK DISEASE
There is epidemiological evidence and some preliminary reports that trypanotolerant livestock are genetically resistant not only to trypanosomiasis but also to several other diseases of major importance, e.g., tick-borne diseases (anaplasmosis, babesiosis, theileriosis, cowdriosis), dermatophilosis and helminthiosis. For this reason, comparative studies will be undertaken, on-field and on-station, to assess differences in susceptibility within and between the main breeds of the West-African Region, e.g., N'Damas, West-African Shorthorn, Zebus, N'Dama x Zebu, and also trypanotolerant small ruminants. The ultimate objective is the development of a socio-economically sustainable strategy for the control of the most important diseases of livestock in the West-African region through the increased use of genetically resistant animals.
6. TSETSE ECOLOGY AND ENVIRONMENT
ITC will continue to coordinate the collection of data, using standardised methods on tsetse, livestock and the environment throughout the sub-region. The relationship between tsetse challenge and productivity will be determined by the manipulation of tsetse populations through strategic reduction of challenge. Special attention will be given to full community participation and monitoring cost and benefits to the rural population. In collaboration with DLS (Gambia) and appropriate NARS, studies will be undertaken to assess the long-term demographic and environmental trends, relative to the growth and productivity of livestock populations, and the evaluation of the tsetse/trypanosome risk.
The tsetse programme will continue to provide infected flies for the station and village selection programmes.
7. TRAINING AND INFORMATION
Training activities will be continued and developed through:
in-service training of national scientists,
training courses for participants from the whole sub-region,
national and regional seminars/workshops,
fellowships and study tours in other African countries, and
external training for a limited number of scientists for higher academic degrees or for specialisation in fields related to trypanotolerant livestock development.
Increased efforts will be made to collect, analyze and disseminate all information related to trypanotolerant livestock, by running a specialised documentation centre, by initiating a question /answer service and by publication.