The Repeatability of Grazing Efficiency as a Perennial Ryegrass Variety Trait

The ‘Grazing Utilization’ sub-index within the Pasture Profit Index identifies perennial ryegrass varieties with high grazing efficiency. Grazing efficiency is assessed in plot trials conducted over a number of years. The objective of this study was to investigate the repeatability of variety grazing efficiency. Correlations were derived between variety performance in separate evaluation years and between variety performances in separate trials. Grazing efficiency was found to be moderately repeatable, with correlation values ranging from 0.47 to 0.86 between years and ranging from 0.51 to 0.84 between trials. The results will provide commercial seed companies with increased confidence when developing variety mixes intended for intensive grazing. Farmers will benefit from improved variety selection and animal performance from their farms.