Simulation of wool growth rate and fleece characteristics of Merino sheep in Southern Australia. Part 2—Assessment of biological components of the model

Abstract

The first paper in this series described the development of procedures for predicting the effect of management changes on wool growth rate and fleece characteristics. A model of a self-replacing flock of Merino ewes was modified to provide weekly predictions of wool growth rate, fibre diameter, staple length and staple strength. This paper presents the results of a comparison of biological predictions of the model with field observations collected under a range of seasonal conditions and stocking rates. The results of the comparisons demonstrated the ability of the model to mimic the seasonal pattern of events and the trends in pasture and sheep performance generated by a wide range of stocking rates. The model successfully predicted the direct effects of stocking rate and changing seasonal conditions, as well as the interactions between them. For most of the fleece data, the model predictions were well within one standard deviation of the field observations. No major biases in the predictions of the model were evident.