Relationships between pasture availability, wool profile and staple strength in various sheep grazing environments

Information on variation in fibre diameter during the wool growing season derived using optical fibre diameter analysis (OFDA2000) can be used to predict wool staple strength. Information on fibre diameter can also be used to initiate nutritional management strategies for preventing wool tenderness and the associated price reduction. However, OFDA2000 measurements involve costs associated with the collection of mid-side wool samples and laboratory analyses. In addition, the information is retrospective, as results are usually obtained too late for feeding and management interventions. We investigated the use of real-time pasture availability data obtained using satellite imaging to predict fibre diameter profile and staple strength. Correlations between pasture availability and changes in fibre diameter were strong, but varied between environments. In general, the rate of reduction in pasture availability was moderately correlated with the reduction in fibre diameter; on average it accounted for 28% of the variation in fibre diameter, and in some environments it accounted for up to 75% of the variation in fibre diameter. The decrease in pasture availability was positively correlated with staple strength and accounted for 26% of the variation in staple strength. The use of satellite-derived pasture availability estimates in feeding strategies designed to prevent wool tenderness is discussed, as is the potential of satellite data for predicting regional staple strength changes.