THE USE OF MODELS IN THE ANALYSIS AND MANAGEMENT OF AQUATIC AND TERRESTRIAL ANIMAL PRODUCTION SYSTEMS

Modelling of animal production systems as a whole is mainly used for e xtensively managed systems, such as fishing and hunting natural animal populations. This type of modelling is widely used in fisheries manag ement, but has as yet found limited application in the modelling of ex tensive cultivation practices. Modelling of terrestrial animal product ion is concentrated on the breeding process and on growth and food con version. For intensive fish culture, modelling concentrates more on gr owth of individual animals. There is a shortage of experience in model ling extensive and semi- intensive cultivation systems, both in aquati c and terrestrial animal production (pond culture, integrated farming) . This paper provides a systematic overview of the types of models in use for animal production systems; these models differ in their contro l over production factors. The state of the art with respect to modell ing subsystems is also sketched. Special attention is paid to the mode lling and prediction of the environmental load caused by the output of present systems and to the search for alternative management strategi es following this whole system approach.