Pasture Quality Measurement Tools for Decision Making

Pasture quality is an important component in grazing and livestock management and a key driver of animal performance. Accurate, real-time information on pasture quality can help farm managers in decision making. This study investigated the potential applicability of optical sensors to estimate pasture quality parameters in the field, these have been trialled as part of the P21 Feed Programme, contract No. C10X0604. This paper summarises the spectral approaches which have been taken to investigate the potential of: 1) The Multispectral approach, where sensing devices (Crop CircleTM and CROPSCANTM) have a limited number of spectral bands, around the VIS and NIR parts of the spectrum with broad spectral resolution, these can be used to estimate pasture quality parameters such as crude protein. 2) A Hyperspectral approach provides fine resolution, using reflectance data spanning from 350 nm to 2500nm, to derive estimates of crude protein, acid detergent fibre, neutral detergent fibre, metabolisable energy, lignin and organic matter digestibility. To extract spectral information and to correlate with reference values, various statistical tools (univariate and multivariate techniques) were used. All in-field measurements were supported by an extensive programme of laboratory NIR and wet chemistry measurements for calibration and validation. Initial results suggest that pasture quality can be accurately estimated using optical sensors and associated statistical methods, providing a useful management tool for farmers. Introduction: In New Zealand, grazed pastures are the main source (85% or more of the total feed) for livestock feed, hence it is considered economically significant. In pasture management, measurements of pasture quantity are an essential operation for efficient feed management and to improve animal performance (Holmes, et al., 2007). To this date, pasture mangers used a wide range of mainly pedestrian quantity measurement devices in decision making. More recently the C-Dax Pasture Meter ® has been used; this is attached to an ATV and provides rapid measurement of pasture as well as integrating with farm management software to provide a more efficient measurement system. Although a significant step forward, quantity based decision may still have their limitations as pasture quality is variable through seasonal and management effects, these influence animal performance. Consequently, quality based decision making approaches are being developed; thereby animal performance could be improved by optimising the pasture component of the diet. These would be used in conjunction with pasture quantity methods to establish the total nutrient availability in a