Evaluation of a beef growth model for use in beef finishing decisions

Specif icat ions A decision support computer program for beef finishing, called BoVision, is described. It is based on biological models of animal and pasture growth, and is designed to assist the user in making strategic and tactical decisions about their beef finishing operation. Examples of its uses are to answer questions regarding profitability of l-year versus 2-year-old cattle policies, the optimum stocking rate, and the profitability of local trade versus prime versus bull beef. BoVision can also be used to evaluate premiums required for out-of-season beef, the economics of nitrogen use and supplementary feeding. It can also be used to perform sensitivity analyses. An important aspect of the program’s development process was the involvement of a group of beef finishing farmers. The animal growth and pasture intake models used are presented. This paper backgrounds the program’s development, and evaluates its use in predicting Angus steer performance for a trial conducted at Whatawhata Research Centre. Performance for a Friesian bull trial is also evaluated. Implications for BoVision’s use on farms are discussed. The program was developed using Turbo Pascal, and runs on IBM PC compatible computers. A graphic in terface , wi th pul l -down menus, d ia logue boxes and spreadsheet-like data entry cells have ensured that the program is easy to learn, and intuitive to use. The involvement of a group of target users has ensured BoVision’s ease of use, and relevance to beef farmers. Required input BoVision operates by modelling the pasture and animal components of a beef f inishing operat ion. I t requires the user to enter information specifying details of their operation in the form of policies to be analysed. A set of policies and associated information constitutes a farm and this information is saved by the program into a file on the computer’s disk.