A simulation model of draught animal power in smallholder farming systems. Part I: Context and structural overview

This paper presents the context, approach, and overview of a computer based draught animal power simulation model named Draught Animal Power Simulator (DAP-Simulator). The model was developed using data from literature and modified components and modules of existing models. The overall objective of this study was to provide a decision support system for agricultural planners and development agencies in the evaluation of different strategies of improving the efficiency of DAP use in crop production. The model was coded in Turbo PASCAL 7.0 and implemented in the interactive modelling package, DRIVER. The traction module of the PCHERD model was modified and interfaced with dynamic, empirical and deterministic sub-routines that simulate energy requirements for work (ploughing or carting loads), maintenance, pregnancy, lactation, feed intake, digestion and absorption, and daily weight changes. It can be used as a tool for the strategic use of draught animals, estimating effects of work stress on animal performance and calculation of work requirements. The development of this model indicated that more research work needs to be carried out in quantifying rolling resistance; estimating specific soil resistance, energy requirements for maintenance in Bos indicus cattle; effects of disease; animal behaviour (temperament), and partition of endogenous and exogenous energy. A subsequent paper will present detailed descriptions of model validation, sensitivity analysis, and application.