From its establishment in 1972 to now, the CRTA was involved mainly in four areas of activities:
Applied research to control West African tsetse population through sound pest management and nonpolluting techniques.
Epidemiology of animal trypanosomiasis in view of improvement of health situation of village livestock.
Investigation on natural resistance of indigenous breeds, including mostly Baoule West-African Shorthorn.
Training of national expertise mostly at medium level and graduate level.
Since, this consultation is on the Genetic aspects of trypanotolerance, this presentation will focus on that particular point: the natural resistance of indigenous breeds.
The following are to be presented:
The achievements by research teams.
The ongoing activities and the prospects.
Ideas on trypanotolerance livestock and germplasm enhancement.
Possible common programmes as cooperative research and/or contractual research.
The achievement were on:
Immunogenetic characterization of taurine breeds.
Parasitological screening of Baoule at village level.
Evaluation of the reproductive and physiological parameters of the Baoule breed.
Establishment of semen bank including collections from defines animals.
Immunogenetic characterization was performed on both Baoule and Ndama breeds. It consisted of screening for protein polymorphism (mainly albumin and haemoglobin) and typing of bovine lymphocyte/antigens (Bola). It was demonstrated that higher resistance was attached to individual Baoule or Ndama cattle both homozygote FF for albumin and AA for haemoglobin. However, the frequency of gene F for albumin within the Baoule
breed showed a higher variability according to the herds surveyed at different location. Concerning Bola, survey in the Lobi Country, South of Burkina Faso, performed on more than 1,000 Baoulé at village level, only confirmed the value of the double test albumin FF - haemoglobin AA for higher resistance. However, Bola was used to screen Baoulé animals classified as (R) : resistant or (s): sensitive in four (4) different geographical areas having different tsetse challenge. Up to 200 Baoulé were evaluated in 1989 for Bola class 1 specificities (team: Maillant - Queval) - Surveyed population was expanded to reach 2,000 animals.
Field screening for resistance was associated to laboratory experiments using naive animals both Zebu and Baoulé in fly-prof stables. At Satiri, Clausen and his colleagues exposed in 1987, 64 Ba and 20 Z to high challenge. There were indication that in both breeds previous exposure to natural infection induced enhanced capacity to control parasitemia. However, for the Zebu, this was not correlated to a capacity to control anaemia. In Baoule breed, a low PCV following some weeks of high tsetse challenge has also given a good idea on the degree of tolerance. Some other analyses were on Zinc profile and other mineral and also high density lipoproteins.
Other studies on trypanotolerance included host-parasite relationship, for instance natural attractivity of tsetse to specific breéds; the induction of chancre; the immune response.
All these aimed at identifying highly resistant Baoulé for multiplication. Some results were published, in 1987 by Roelants, Fumoux, Queval et al in which it appeared that crossing resistant-resistant Baoulé between them provided higher grade germplasm in terms of resistance.
It is worth noting that the Baoulé breed is prevalent in the sub-humid zone (in Côte d'Ivoire, Burkina Faso, Ghana, Togo, Benin, Nigeria) Bur under different names. In addition to Baoulé, the CRTA has access to numbers of non-defined crosses between Ndame and Zebu, Baoulé and Zebu and pure zebu now in fair numbers within the tsetse belt.
The reproductive physiological parameters of the Baoule were also investigated aiming at artificial insemination.
A small collection of 10,000 doses of pure Baoulé semen is maintained for experimental purpose.
Most of the ongoing activities are both laboratory and field activities. Baoulé cattle is surveyed mainly in the Lobi Country where pure breed is still existent in large numbers. Other sites allow screening of Zebu and crosses: Samandeni, Satiri, Samoragouan, etc. It is planned to enlarge the CRTA which will ecome an international subregional centre. Among the programmes of the new Centre, trypanotolerance and trypanotolerant livestock will have a high rank of priority. The research areas will be:
Evaluation of trypanotolerance in livestock.
Field selection of high grade resistant animals.
Improvement conformation of trypanotolerant livestock.
A whole set of animal husbandry packageś for the highest possible production of trypanotolerant livestock.
Then comes the need to clarify again in this consultation some ideas and attitudes on trypanotolerant livestock.
Yes, trypanotolerance is an excellent genetic trait which must be preserved and multiplied.
The number of trypanotolerant livestock, if not decreasing, is not increasing at such a level that it would develop soon vast areas of sub-humid zones. In fact crossing with the Zebus by the herders themselves is more and more frequent.
Therefore research should aim at creating new germplasm with enhanced resistance and large conformation associated to high yield of meat and milk.
M. Chairman, I am not a geneticist, therefore, I cannot exactly tell how to. The need is expressed and we must reach that goal using the most advanced biotechniques.
The CRTA will cooperate with any institution which shares a common goal. Mapping of trypanotolerant animal genes is one of the candidate programmes for which a new network should be established and funded. The CRTA has access to diverse ecological situations where animal population, fly challenge, breeding systems vary and therefore provide background for sound knowledge of investigated phenomenons.