Survey methods to estimate demographic rates of tropical ruminant livestock herds. Review, limits and prospects

Abstract

Demography is a key determinant of the production of ruminant livestock herds raised under extensive tropical conditions. Estimation of demographic rates (reproduction, mortality and offtake) is necessary to assess the impacts of husbandry or health interventions on herd production. This estimation is however particularly difficult and constraining. Traditional livestock systems pose major specific problems when attempting to collect data from herds. This paper reviews survey methods used in villages to estimate demographic rates of ruminants, i.e. individual animal-based monitoring, herd monitoring without individual identification of animals, and retrospective cross-sectional surveys. Research perspectives are proposed to improve methods, especially in the context of longitudinal surveys that include interannual variability of demographic rates.