reduces livestock productivity due to poor growth, weight loss, low milk yield, infertility and
abortion. Other losses emanate from farmer’s responses to the perceived risk of the disease
and may include reduction in herd size and reduced crop production due to insufficient animal
draft power. It is estimated that control of trypanosomosis would result in substantial
increases of milk and meat supply in sub-Saharan Africa by a substantial 17 percent (De Haan
and Bekure, 1991).
Control of trypanosomosis in Africa currently relies largely on the use of
chemotherapeutic drugs, tsetse vector control or an integrated control approach combining
several strategies. In most cases, such control remains costly and only partially effective. The
control of trypanosomosis using trypanocidal drugs to treat or prevent the disease is limited
by drug costs and availability, and by the development of drug-resistance in target parasites.
Genetically controlled tolerance of livestock is a highly promising route for control of
trypanosomosis (d’Ieteren et al., 1998). The advantage of genetic control over other methods
of control is that genetic changes are cumulate and permanent, and there are no recurring
costs to the end users. The prospects for producing cattle with genetic tolerance to
trypanosomosis in combination with other suitable characteristics are high given that
trypanotolerance is known to exist in several cattle populations.
Breed improvement, provides key entry points for increasing productivity in cattle
populations especially those susceptible to trypanosomosis. However, there are tendencies for
breed improvement programs to focus on single, market driven traits such as milk or meat
production in isolation of broader livestock system functions and constraints. The focus of
livestock development policies in developing countries has often been on improvement of
livestock productivity through substitution of large-frame, higher yielding exotic breeds for
indigenous breeds. This has repercussions on potential loss of indigenous livestock breeds,
which are more adaptable to the harsh climatic conditions in some environments and capable
of fulfilling the multiple roles that cattle assume in developing countries.