‘SummerPack’, a user-friendly simulation software for the management of sheep grazing dry pastures or stubbles

Abstract

‘SummerPack’ is an interactive computer package aimed at assisting farmers and agricultural advisers with the management of sheep over the summer/autumn period in a Mediterranean environment. The program provides predictions through time of sheep liveweights, herbage on offer, diet digestibility, maintenance requirements and digestible dry matter intake. The amount of supplementary feed necessary to carry the sheep until the next autumn break can be determined. The inputs used in the program are: initial amount of dry herbage on offer and digestibility of the various herbage components, natural decline rates in dry matter on offer and in digestibility, initial liveweight and type of sheep. Although a green pick can be included, the program does not simulate pasture growth. The simulation model on which ‘SummerPack’ is based is described in detail. The herbage is composed of up to five components and preference coefficients are defined that provide a simple way to derive diet composition from the proportion of each component in the herbage. The sheep flock can be split into five liveweight classes that account for the variation in size of the animals. The model has been tested against the results of a stocking rate experiment conducted in Katanning, Western Australia. The model is currently being used at the Western Australian Department of Agriculture for extension and research. Applications are described, ranging from the early on-farm planning of supplementary feeding requirements to the analysis of trial data and assistance in the assessment of research proposals.