Trypanotolerance in Djallonke sheep and West African Dwarf goats : Importance of trypanosomosis, nutrition, helminth infections and management factors

Abstract

The main breeds of sheep and goats in The Gambia, the Djallonke sheep and West African Dwarf goats are trypanotolerant. The Djallonke sheep, however, have a higher degree of trypanotolerance than the WAD goats. This trait is genetically linked although the mechanism of trypanotolerance is different from the one in cattle. It is defined as a resilience to infection rather than resistance. Both breeds are well adapted to the locally prevailing diseases and environmental conditions under which they live. Moreover, they feature the capacity of making good use of low quality feed resources. For the rural farmer, small ruminant production is an attractive enterprise and seems to be profitable even under a low input management system. Small ruminant production also has a large potential under more intensified peri-urban conditions. Trypanosomosis remains an important constraint to optimal productivity. In particular when combined with other diseases, poor nutritional status and poor husbandry practises there is a clear effect on productivity and thus profitability. All these factors should be regarded as equally important. Based on the results of research and surveys presented in this thesis, some recommendations are formulated for interventions in order to reduce the disease constraint, improve the nutritional status and adapt the management of small ruminant production systems. Further research will be carried out to study the impact of the proposed interventions and their adaptation to the local conditions.