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This paper demonstrates the verification and validation of the mathematical relationships for a summer rainfall version of SheepO (version 4.0), a Decision Support System that simulates pasture and sheep production. SheepO (version 3.0) was primarily developed for the winter rainfall areas of Southern Australia and over predicted the available pasture in a summer rainfall environment. These differences have led to the implementation and development of three regional models: water balance, digestibility and shoot death. The development phase used production data for fine wool Merino wethers (4–5 years old) grazing on a Phalaris/White clover pasture (Armidale, Lat. 30°, 31′S, Alt. 1070 m). The verification of version 4.0 shows the calibration of pasture and sheep production at a low (9.9 sheep/ ha) stocking rate and the experimentation of making one management change to a high stocking rate (19.8 sheep/ha). Similarly, validation is shown using an independent data set (Glen Innes, Lat. 29°, 42′S, Alt. 1057 m) of fine wool Merino wethers (8 months old) at low and high stocking rates, respectively 10 and 15 sheep/ha. SheepO version 4.0 will now assist advisers, producers and researchers in a summer rainfall environment to investigate the outcome of changes to current management strategies. |
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