POTENTIAL OF TRYPANOTOLERANCE AS A CONTRIBUTION TO SUSTAINABLE LIVESTOCK PRODUCTION IN TSETSE AFFECTED AFRICA

Tsetse transmitted trypanosomiasis is possibly the major constraint on livestock and agriculture development in Subsaharan Africa. Control o f the disease has been based on vector control as well as on the use o f trypanocidal drugs to treat or prevent infection in animals. Both co ntrol methods are effective but have proven not to be sustainable. Mor eover, the development of a vaccine against trypanosomiasis is unlikel y to be successful in the near future. On the other hand, trypanotoler ant cattle, like the N'Dama can survive and produce in tsetse affected areas without interventions. This taurine breed has been indigenous t o Africa for approximately 7,000 years and forms presently about 6% of the bovine population of Africa. Generally the N'Dama are kept in the rural areas by the small-scale farmer as a multi-purpose animal. Rece nt studies have defined management characteristics and assessed the pr oduction potential at the village level and under ranching conditions of N'Dama cattle exposed to various levels of tsetse challenge. Furthe rmore, experimental infections showed conclusively the superior resist ance to the effects of infection of the N'Dama cattle when compared to zebu cattle and have confirmed that trypanotolerance is innate in N'D ama cattle. Studies have been conducted on development of protective h umoral and cellular responses, the regulation of parasite multiplicati on and control of anaemia. These studies provided tools for identifyin g components of trypanotolerance. The ability to resist the developmen t of anaemia in the face of infection, has shown to be correlated with the capacity to be productive; moreover, PCV values can serve as sele ction criterium for trypanotolerance. Subsequently, repeatabilities an d heritabilities of trypanotolerance and performance traits were estim ated. Economically sound selective breeding programmes for increased p roduction and trypanotolerance are now feasible. Finally, studies have been initiated to identify genetic markers to clarify the relationshi p between genetic variation at the molecular level and variation in tr ypanotolerance. It is envisaged that in the next decade genetic improv ement can be achieved by applying marker assisted selection and introg ression of trypanotolerance to other breeds.