摘要：The BeefSpecs fat calculator was conceived as a means of combining data from growth path studies with knowledge contained in animal growth and body composition models to make predictions of cattle body composition using on-farm measurements. This would assist producers to make critical management decisions that affect their ability to meet market specifications. The first phase of BeefSpecs was based on a multiple regression interpolation of the simulation results from an animal growth and body composition model called the Davis Growth Model (DGM). The agreement between observed and predicted P8 fat depths using this approach was relatively high. However, there are certain circumstances where the multiple regression method produces poor agreement with observed P8 fat depths. The second phase of BeefSpecs has involved the departure from the multiple linear regression approach and direct use of an alternative animal growth model (Williams and Jenkins model, WJ). Agreement between observed and predicted P8 fat depths using this model has generally been similar to that experienced in phase one. However, in circumstances where phase one had problems predicting P8 fat depth the WJ model has provided much more robust predictions. Work is progressing to extend BeefSpecs‘ capabilities by predicting retail meat yield from on-farm measurements. These refinements of the BeefSpecs calculator have allowed the development of other tools that 'hang off' BeefSpecs to progress to the preliminary testing stage. A tool for on-farm drafting has been developed that allows producers to explore the effects that management changes have on the ability of groups of animals to meet market specifications. An additional tool has been developed that is targeted at refining how pen allocations occur in feedlots to help reduce the days on feed needed by certain animals and increase overall production-system profit.
