An expert system for sheep drenching

Abstract

The animal grazing industry is a major sector of New Zealand's economy. Managers controlling the utilisation of the nation's massive pasture production tend to make utilisation decisions using experience and intuition in constrast to formal analyses. Yet, when related to the potential, production achieved tends to suggest improvements are possible. That is, greater production is possible with the same resources, or alternatively the same production is possible from a smaller resource input. It appears one of the reasons for the lack of formal planning is the farmers' belief that the work involved is not commensurate with the gains. Thus, if techniques that are simple to use and provide an efficiency gain can be found they clearly have potential. The study reported in this Report concerns the development of an expert system for a small component of the grazing management problem. It is proposed that such an expert system meets these requirements. This report is one of a series describing several expert systems in the area of grazing management. Another contains an evaluation of these expert systems. An expert system is a set of knowledge and decision rules, usually computer-based for ease of access and retrieval, gleaned from experts (thus the term expert system) and made widely available to decision makers so they can gain the benefits of the experts knowledge and experience. Essentially, creating an expert system involves questioning the experts to find out the factors they observe, and the conclusions they reach given the various values the factors or parameters can take on. This information is then computerised. Grazing management involves many aspects. A single system that would cover all components would be extremely valuable, but it would be unmanageable. Thus, it needs to be broken into practicable sections. Three problems frequently mentioned by farmers are the selection of weaning date, deciding whether to drench, and deciding when to close an area of pasture for conservation. While there are also many others, the importance, in terms of farmers' comments, of these three meant they were selected for study. This Report contains a description of the drenching expert system. Drenching practice has been an area of scientific study. Consequently, there is a body of research available to form an underpinning for advisers. One of the experts that needs consulting is this body of research. From the literature the set of important factors was isolated, and the rules on whether to drench a group of ewes or lambs for each set of values was isolated. These if-then rules were then presented to a committee of animal science and veterinary experts, as well as an experienced farm consultant, for review.