The improvement of milk production is a major goal of the Sudanese government to ensure sufficient and healthy nutrition and to increase the income in rural areas. To reach the goal, it is necessary to improve the herd management and feeding practices in the short-term and to establish an effective long-term animal breeding strategy. This can be achieved through improving the performance of indigenous breeds and its crosses. Among the indigenous breeds in Sudan, the Bos indicus Zebu cattle Butana is the most-widely used breed for milk production. Butana is known for its adoption to the extreme environmental conditions in Sudan, such as hot climate, low feed availability, lack of water, and tropical diseases and parasites. To increase the productivity of Butana cattle, they were crossed with the high-yielding dairy breed Holstein Friesian. Further, their productivity could be improved by genetic selection for higher milk yield or decreasing susceptibility to mastitis, the main dairy disease affecting milk production worldwide. Therefore, this thesis aimed at contributing to develop such breeding programs for Sudan. The specific aims were (1) the evaluation of the productivity of Sudanese purebred Butana and Butana × Holstein crossbred cattle reared under different management conditions and feeding systems, (2) the analysis of the incidence of mastitis and testing its linkage to known genetic markers in purebred Butana and in Butana × Holstein crossbred cattle as well as in a German Holstein population, and (3) the investigation of the genetic effects of the diacylglycerol acyl transferase 1 (DGAT1) gene as the major gene affecting milk yield and composition in Holstein cattle on the milk yield, fat and protein content in purebred Butana and Butana x Holstein crossbred cattle in Sudan.weiterlesen