Evaluation of health and productivity of small ruminants in Africa: the example of Senegal.

The authors describe a system of investigation introduced into Senegal in 1983; their purpose is to extend knowledge about the farming of small ruminants and the epidemiological relevance of such farming. The investigations are conducted in the traditional livestock sector by using a multidisciplinary approach. The precision and reliability of the information depend on the recording and processing of data on individual animals. The system of investigation has a modular structure organised around a central module for demographic surveys. The peripheral modules correspond to specific activities: clinical surveillance, recording changes in body state, laboratory tests and a study of animal husbandry conditions and practices. The authors distinguish four levels of analysis depending on the origin of variables under consideration: a single module (level 1), the demographic module plus the peripheral module (level 2), the demographic module plus two or more peripheral modules (level 3) and one or more modules derived from experimental modification of certain features of the husbandry system (level 4). The constraints and limitations of the procedure are discussed.