The repeatability of perennial ryegrass grazing efficiency as measured by Residual Grazed Height

International audienceA key grassland management strategy is to graze to low post-grazing height (4 cm) to maximize grass utilization and maintain/increase sward quality in future rotations. Perennial ryegrass varieties differ in their ability to be grazed to low post-grazing heights, as indicated from on-farm variety assessments and plot studies. Residual grazed height has been developed as a measure of perennial ryegrass variety grazing efficiency and has been included as a trait within the 2021 pasture profit index (PPI). The PPI is a variety selection tool used by the Irish seed industry. Variety grazing efficiency has been evaluated since 2015, but only now enough data exist from a number of studies to investigate the long-term variety grazing efficiency. The current study analysed data from four perennial ryegrass plot evaluations. Moderate to strong correlations were found between trials and evaluation years indicating that variety grazing efficiency is a repeatable trait. Such results provide confidence to the seed industry when making variety selections decisions