Field studies influence of environmental factors and susceptibility to trypanosomosis of the Boran and Boran-N'dama crossbreed cattle in Kenya
Munga, Karongo Leonard
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Trypanosomosis is a disease of humans and domestic animals caused by protozoan parasites of the genus Trypanosoma and mainly transmitted by tsetse flies (Glossina). The current methods for trypanosomosis control include vector control, treatment with trypanocidal drugs and keeping trypanotolerant livestock. The main advantage of keeping trypanotolerant animals is that it requires realtively lower recurrent expenditures, and is therefore suitable for low income production systems. The N'Dama of West Africa is the most important among trypanotolerant cattle, and some degree of trypanotolerance has also been observed in the Orma Boran of East Africa. The N'Dama is widely used in West Africa but there is no information on the potential value of the N'Dama in East Africa. In addition, there is lack of information on how the environmental conditions influence trypanosomosis in cattle. The objectives of this study were to compare infection rates, disease severity, treatment requirement and the ability of Kenya Boran and their crossbreeds with N'Dama cattle to survive under natural tsetse challenge and to determine hoe the preveiling environmental conditions influenced the disease in cattle. The study animals consisted of 335 cattle of four cattle breeds, namely Orma Boran (OB), Kenya Boran (KB), F1 N'Dama X Kenya Boran (NB) and backcross of Kenya Boran on F1 N'Dama X Kenya Boran. The cattle were produced in a tsetse free area and taken to the field site in Narok in six successive groups which were exposed to high tsetse challenge for at least one year. The animals were examined regularly for trypanosome infection, development of anaemia, growth rate and treatment requirement. The result of this study showed that increase ambient temperature was significantly associated with increase disease incidence in cattle while inreased normalised difference vegetation index (NDVI) had negative correlation with trypanosome incidence and persistence of parasitaemia in the cattle. Among the four cattle genotypes, the F1 N'Dama X Kenya Boran was the least susceptible. The orma Baran was less susceptible than the Kenya Boran and the backcross of the Kenya Boran. It was concluded that the N'Dama could play a role in enhancing trypanotolerance in the Kenya Boran cattle and the Orma Boran was more suitable that the Kenya Boran for crossbreeding with the N'Dama. It was also recommended that in development of livestock breeds for the tsetse infected arid and semi arid areas of Kenya should take into considerable the environmental conditions in these areas.