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Accueil du site → Doctorat → États-Unis → 1994 → Optimization of pastoral subsistence strategies under drought and marketing risks : Maasai model ranch study

Colorado State University (1994)

Optimization of pastoral subsistence strategies under drought and marketing risks : Maasai model ranch study

Mwangi, Lucy Ngendo

Titre : Optimization of pastoral subsistence strategies under drought and marketing risks : Maasai model ranch study

Auteur : Mwangi, Lucy Ngendo

Université de soutenance : Colorado State University

Grade : Doctor of Philosophy 1994

Résumé
Maasai pastoralists have adopted drought coping strategies with the ultimate goal of securing sufficient human food. Three energy sources were considered in this study, grain, milk, and meat. A major assumption was that pastoralists can obtain these three food types by manipulating their livestock herds. Four activities through which pastoralists manipulate their herds were explored : (1) sale of livestock to purchase grain, (2) sale of milk to purchase grain, (3) direct milk consumption, and (4) slaughtering of animals for human consumption. The aim of this study was to show how Maasai households can attain optimal expected return in energy by combining these four activities under drought and market risk. For practical purposes a model ranch of 10,000 hectares, which is a type of existing group ranches, was defined. Three model households of different wealth classes were defined on the basis of livestock ownership and accessibility to grazing area. Two types of pastoral drought strategies were examined : (1) transfer of energy reserves from boom years to bust years, and (2) temporary human migration from pastoral systems during drought. Migration of people from the system during drought was incorporated in the model by lowering target energy defined for a household for that period. Target-Motad (Minimization Of Total Absolute Deviations), a probabilistic linear programming model, was used to obtain optimal expected returns at various risk levels while meeting a target subsistence energy level defined for a household. Target-Motad models were developed using information on long-term livestock productivity parameters simulated by i.l.c.a. using 50-year rainfall data. A planning horizon of 30 years was assumed. Target-Motad solutions provided estimates of energy surpluses in boom years that can be transferred to bust years. Model solutions also provided different levels of energy acquiring activities which were used to define minimum subsistence herds for households. Poor households were found to be the most drought vulnerable wealth group in Maasailand. Year type sequencing had a great impact on household subsistence conditions during drought. The first year of drought has better subsistence conditions than a second year because of energy transfer from boom years. Marginal analysis of risk-return results indicated that risk seeking behavior is rational for rich households. Poor and medium-rich households should adopt less risky plans in order to survive.

Mots clés : Masai (African people) ; Livestoc ; Agricultural economics ; Masailand, Kenya ; Pastoralists

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Page publiée le 3 décembre 2013, mise à jour le 18 novembre 2018