Calibration equations are available to determine the dry matter (DM) mass of pasture using either sward height or plate meter readings. Currently there are no methods available for determining DM in a herb-clover mix other than using quadrat cuts. The objective of this research was to determine the relationships between herbage DM mass as measured by quadrat cuts vs sward height and plate meter readings for herb-clover mixes during four seasons from early spring to autumn. Pre- and post-grazing herbage DM masses (kg/ha) in the plantain mix (plantain (Plantago lanceolata), white clover (Trifolium repens) and red clover (T. pratense)) and in the chicory mix (plantain, chicory (Cichorium intybus), white clover and red clover) were estimated by collecting quadrat cuts. For each quadrat cut, a plate meter reading and five sward height measurements were also recorded. Separate regression equations were then developed for quadrat herbage DM mass vs sward height and plate meter readings. In addition, data from the plantain and Chicory mixes were pooled to obtain a data set for a combined herb-clover mix. The individual R 2 values were significant for all three relationships and ranged from 0.49 to 0.86. The concordance correlation coefficient (CCC) for all three relationships fell between 0.56 and 0.94. The relative prediction error (RPE) for all three relationships varied between 18 and 29%. The regression equations developed by these non destructive methods, would enable farmers to obtain a reliable estimate of the herbage DM mass, with a level of precision sufficient for making day-to-day grazing management decisions on farm. The data do suggest different regression equations need to be utilised for different seasons of the year.

SC, Somasiri, PR Kenyon, PCH Morel, PD Kemp, and ST Morris

Proceedings of the New Zealand Society of Animal Production, Volume 74, Napier, 115-120, 2014
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