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Calculation of demographic parameters in tropical livestock herds : a discrete time approach with LASER animal-based monitoring data

Lesnoff M., Lancelot R., Moulin C.H., Messad S., Juanes X., Sahut C.. 2014. Dordrecht : Springer [Pays-Bas], 109 p..

Présentation de l'éditeur : Ruminant livestock (cattle, small ruminants, and camels) have a determinant economic role in many tropical developing countries. In traditional low-input farming systems, demographic parameters (e.g. reproduction or mortality rates) are important indicators for estimating and modelling herd dynamics and production, and impacts of farming practices or environmental risks (droughts, epizootics, etc.). Although such parameters have been extensively described in the literature on tropical livestock, many descriptions only rely on empirical presentations of formulas without clear methodological justifications. This book fills this gap, presenting the main concepts used to define and compute demographic parameters for tropical livestock, such as probabilities and hazard rates of occurrences and competing risks. It is based on the LASER software, a relational database management system specifically designed for animal-based monitoring surveys. It also provides an introduction on R, the free statistical software (http://www.r-project.org) used for the computations. It is intended for researchers, engineers, technicians, or students dealing with demographic parameters of tropical ruminant livestock in various fields such as animal science, epidemiology, or economy. It will also be valuable for readers wishing to enhance their understanding of definitions and formulas found in the literature, and it will guide them in their applications. Contents: 1. Introduction. 1.1. Background and objectives. 1.2. Animal-based monitoring. 1.3. A selection of parameters. 1.4. Organization of the handbook. 2. Grouping demographic data. 2.1. Cohort splitting. 2.2. Pseudo-cohort splitting. 3. Mortality and offtake rates. 3.1. One type of removal. 3.2. Case with two types of removal. 3.3. Additional points. 4. Other demographic rates. 4.1. Reproduction rates. 4.2. Synthetic rates. 4.3. Global demographic rates. 5. Package Laserdemog. 5.1. R software. 5.2. Functions in Laserdemog. 5.3. Additional points. 6. Numerical examples. 6.1. Example 1 - Overall description. 6.2. Example 2 - More on reproduction rates. 6.3. Example 3 - Test of a treatment on mortality. 7. Annexes. 7.1. Rates p and h in survival analyses. 7.2. R materials. 7.3. Structure of tables generated by hsplit and vsplit. 8. Bibliography

Mots-clés : sécheresse; facteur du milieu; méthodologie; méthode statistique; laser; dynamique des populations; zone tropicale; banque de données; donnée statistique; statistique démographique; troupeau; mali

Thématique : Méthodes mathématiques et statistiques; Elevage - Considérations générales

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