Genetische Charakterisierung von Rinderrassen in Burkina Faso zur Trypanosomiasis-Toleranz

In the sub - Saharan area of Africa, trypanosomosis is the most important disease transmitted by vectors to cattle and constitutes a major obstacle to the development of livestock in this region. Africa has more than 200 million cattle, approximately one quarter in regions infested with tsetse flies (FAO, 1997). The annual productivity deficit represents 1 million tons of meat and 1.6 million tons of milk. In Burkina Faso, animal breeding constitutes an important source of income for the national economy, 19% of exports and 12% of the GDP (MRA, 1997). Cattle is the dominant species (more than 4,5 million heads) with an important population of Peul zebu. The country is in an endemic area so the livestock suffers the consequences of trypanosomosis. Direct losses (mortality) are aggravated by indirect losses due to low growth rate, morbidity and problems of reproduction, often difficult to be quantified (abortion, sterility, increase in the interval between calving). According to the World Bank, income losses in agriculture vary between 800 and 1600 mio. US dollars depending on the degree of trypanosomosis. These losses lead to a decrease of available food protein for the population Burkina Faso is an interesting area for studying the effects of natural selection for trypanomosis tolerance in cattle. The North of the country is free of tsetse whereas to the South is heavily infested. Burkina Faso hosts populations of trypanotolerant breeds (Taurine) and susceptible breeds (Zebuine): The primary goal of of the thesis work is to identify and compare patterns of selection in the genome of breeds inhabiting both, unchallenged and challenged areas. Therefore the results will contribute to the genetic characterization of livestock regarding non neutral genetic variation. Differences between taurine and zebuine cattle exposed to different levels of tsetse challenge will be highlighted. The major interest is to find differences in the genetic variation of trypanosome tolerance genes compared to regions of the genome neutral to selection. Such results will serve as confirmation of the outcomes of other projects with pure N’Dama cattle, but further it is aimed to find a way to distinguish whether a certain part of an animal’s genome originates from taurine or zebuine based on SNP information. A comparison of selection patterns between different areas of challenge and different composites of breeds will be carried out.