Trypanotolerant cattle, sheep and goat populations are described, covering an area of 4.67 million km2 in 18 countries of West and Central Africa. Animal numbers include approximately 3.4 million N'Dama cattle, 1.8 million West African Shorthorn, 2.4 million Zebu x N'Dama or West African Shorthorn crosses, 11.5 million sheep and 15 million goats. Groups, breeds and varieties are classified and numbers, distribution, environment, breed characters, husbandry systems and performances are described; The N'Dama group appears to be increasing in numbers and the Savanna Shorthorn seem to be declining fairly slowly and the Dwarf Shorthorn more rapidly, both mainly through crossbreeding over the last decade, resulting in an increase in crossbred cattle types. Sheep and goat populations appear relatively static overall.
The descriptive and performance data clearly show that it is biologically possible to maintain trypanotolerant cattle, sheep and goats in tsetse-infested areas and to establish them in areas where cattle have not previously been bred. Trypanotolerant livestock attain varying degrees of productivity under medium or heavy trypanosomiasis risk which preclude the natural maintenance of non-trypanotolerant types.
In each chapter of Volume 2, whenever sufficient information is available the main production traits are used to build up an index of the total weight of progeny, plus the liveweight equivalent of milk produced in the ease of cattle, both per breeding female per year and per unit weight of breeding female maintained per year. On the basis of the index of total weight of one-year-old calf produced plus the liveweight equivalent of milk produced per 100 kg of cow maintained per year, no significant differences are found between the two main trypanotolerant cattle groups, the N'Dama and the West African Shorthorn. The mean value for both groups is 28.5 kg. The influence of management systems and levels of trypanosomiasis risk is also clearly shown: productivity is 30% lower under village conditions than on ranches or stations, and 27% lower under medium trypanosomiasis risk and 41% lower under high risk than in a low-risk situation. No indication has been found from the limited data available that either Zebu or Zebu x humpless crossbreds are significantly more productive than the two trypanotolerant groups under traditional management and low trypanosomiasis risk. Furthermore, the productivity of trypanotolerant cattle under low trypanosomiasis risk appears from available information to be only 5% lower per unit weight of cow maintained than a wide range of indigenous Zebu and Sanga types maintained in tsetse-free areas of Africa outside the study zone. This suggests, first, that the productivity of trypanotolerant cattle relative to other indigenous types may be much higher than previously assumed, second, that in certain circumstances plans for increased utilization of trypanotolerant cattle may well be immediately justified and, third, that more accurate evaluation is needed of productivity in relation to degree of trypanosomiasis risk and the economic implications. In the ease of trypanotolerant sheep and goats, the results suggest that productivity per unit weight of female maintained may be at least as high as that of a range of other indigenous types in tsetse-free areas throughout Africa. Thus, as with cattle, increased utilization and more accurate evaluation of productivity would appear well justified.
Possibilities are suggested for further evaluation and research to fill the many gaps in knowledge that remain. In virtually all the production situations examined, the information available is not sufficient to allow accurate evaluation of animal productivity or the degree of trypanosomiasis risk. A ease study is presented of a situation in Benin where some basic data have been collected simultaneously on degree of trypanosomiasis and animal productivity. Recommendations and possible locations are presented for cooperative programmes to evaluate the potential and further utilization of trypanotolerant livestock. Conservation requirements are also discussed and measures suggested for conserving some breeds which are in danger of disappearing.
