The relationship between a satellite derived vegetation index and wool fibre diameter profiles

Satellite data provide a systematic and reliable method for recording pasture availability. Pastures from Space (PfS) provides estimates of pasture growth on a weekly basis throughout Australia. The wool fibre diameter profile (FDP) changes in response to feed intake and offers a mechanism for recording the nutritional status of sheep. The aim of this project was to define the nature of the relationship between FDP and a normalized difference vegetation index (NDVI) from PfS. The FDPs and weekly NDVIs were scaled to the same time period for 62 FDPs from 26 flocks throughout Australia. FDP and NDVI were graphed together and relationships were categorised as strong (39), neutral (17) and poor (6). Cross correlation and regression of rate of change of FDP and NDVI curves provide further characterization of the relationship. Supplementary feeding and temperature were factors that may contribute to poor correlations. Where strong relationships exist between FDP and NDVI, they could be used to predict tenderness and average diameter of the wool clip in a region. The relationship could also be used to predict the impacts of climate change on wool production.